This article is an excerpt from a much longer article which you can view here, that gives further quotes on this same topic from others including Sri Ramana Maharshi, Sri Shankara, Suresvara and Ribhu Gita. The original article also gives disclaimer which you should read (ie. these teachings are for earnest seekers only and can have detrimental effects for those not ready for them) and makes some suggestions as how to best appraoch these teachings.

Here are quotes from The Esssence of Ribhu Gita (download the full text here) that contain the Ajata Vada doctrine. Of course the Ribhu Gita itself contains many more quotes that these on Ataja Vada, with almost every chapter hammering home this most radically non-dual teaching:

5. The universe was neither born, nor maintained, nor dissolved; this is the plain truth. The basic screen of pure Being-Awareness-Stillness devoid of all the moving shadow pictures of name and form of the universe is the sole, eternal Existence. (Ch.2, v.33)

9. The universe of name and form, the embodied creatures and their creator, mind, desire, Karma (action), misery and everything other than the Self, are merely thought formations projected by the powers of the Self on its screen — Self. (Ch.5, v.25)

10. The state of firm abidance in that thought-free alert Awareness-Self, constitutes integral perfection, yoga, wisdom, Moksha, Sahaja Samadhi, the state of Siva and the state of Atman-Self, which scriptures proclaim by the title of Brahman. (Ch.5, v.26)

11. There never was a mind nor any of its countless forms like world, jivas, etc. There isn’t the least doubt that all these are the form of the eternally undifferentiable Supreme Brahman-Self. This is the Truth. The one who hears this great secret diligently and understands completely, abides as Brahman-Self (Ch.5, v.28)

14. …That Siva must be meditated upon and realised to be the Self, by making the restless mind stay still and alert after it has been adequately restrained, and completely prevented from the pursuit of sense objects, namely, the shadow pictures on the screen of the Self. All shadow pictures removed, what remains is pure Awareness, the spotlessly effulgent screen. Thus, Siva reveals Himself spontaneously as the sole eternal Sat-Chit-Ananda-Self, the very essence of the nature of the worshipper. (Ch.7, v.35)

24. The total discarding of the mind is alone victory, achievement, bliss, yoga, wisdom and liberation. The sacrifice of the mind is, in fact, the totality of all sacred sacrifices. (Ch.15, v.7)

35. Firmly established in the Self, undisturbed by the least ripple of thought, as still as an idol of stone or wood, dissolved completely in Brahman-Self, even as water is in milk, with awareness devoid of all impurities of thought and drowsiness, standing clear as the pure sky, the grandeur of the Jnani’s nishta (firm stance in the Self) defies thought and expression. (Ch.19, v.21)

40. Abidance in the state of thought-free alert Awareness, is the state of mukti beyond thought and expression. The emergence of thought is the bondage of untold suffering. Abidance in the Self is the true non-dual samadhi, and that alone leads one to the eternal bliss of mukti. (Ch.21, v.41)

43. There are no such things as achieved objectives and the efforts leading to them, association with the wise or the ignorant, efforts of learning and knowledge acquired, acts of enquiry and practice, the learner or the learned, and any goals achieved. What exists is only Brahman, the effulgent Awareness-Self. (Ch.23, v.10)

44. One should be firm in the conviction that there are no charitable acts, sacred waters and kshetras (pilgrim centres), no loss or gain and no loser or gainer, no karma, bhakti and wisdom, and no knower or known. All these thought-forms are bound to be dissolved and lost in the Brahman-Self, which is the sole existence. (Ch.23, v.11)

46. The illusion that one is the body and that the world is the basic reality has remained soaked over a long, long time, and cannot be got rid of by the casual reading and mere understanding of the truth. The basic illusion can be effaced only by a long and unremitting practice of the bhavana that all this is ‘I-am-Brahman-Self’. (Ch.24, v.28)

48. There is never such a thing as conception of names and forms, no such thing as the conceiving mind, no such thing as a person lost in samsara, and no such things as the world and its creator. Everything that is seen to exist must be realised to be no other than the sole, pure Awareness-Being-Brahman-Self. (Ch.25, v.8)

51. By abiding in the Self, the wandering mind is reduced to perfect stillness after being freed from all nescience and thought currents. It gets lost in the Sat-Chit-Ananda-Self in the same way that water is lost when mixed with milk. This unitary state of abidance in the Self is called Atma Nishta by the wise who have attained perfection. (Ch.26, v.2)

54. In that Self wherein there is neither conceiver nor conception of the world of names and forms, one should remain blissfully still, eschewing the least trace of thought. (Ch.26, v.8)

55. In that Self wherein desire, anger, covetousness, confusion, bigotry and envy are all absent; in that Self wherein there is no thought of bondage or release, one should abide blissfully still, eschewing the least ripple of thought. (Ch.26, v.13)

57. Mind merged completely in the Self, one becomes a lord without rival-steeped in bliss beyond compare. In that state one should abide still, free from the least trace of thought. (Ch.26, v.28)

58. I am that Self which is integral existence-awareness-bliss, the sole impartite Brahman-Self. Firm in the conviction born of this experience, one should abide still, free from the least trace of thought. (Ch.26, v.29)

59. In the conviction that ‘I am the Self’ in which no thought, ego, desire, mind or confusion can exist one should abide still, free from trace of thought. (Ch.26, v.31)

60. The firm faith of being the Self is sufficient to dispel all thought and establish one in Brahman-Self. In due course of this practice, even the thought involved in that faith fades away leading to the spontaneous effulgence of the Self. If a person hearkens to this teaching and practises the faith, even if he is a great sinner, he is washed clean of all his sins and is established in Brahman-Self. (Ch.26, v.42)

61. There is certainly no such thing as mind with its constituents of thought and thought forms of objects. In this conviction one should ever abide still and at peace, in the state of thought-free alert Awareness-Self which endures after all sadhanas and its rigours have exhausted themselves in Brahman-Self. (Ch.27, v.29)

62. Having gained the experience that there is no creator, no maya, no duality, and no objects at all, and that pure Awareness-Self alone exists, one should ever remain still and peaceful in that state of Selfhood. (Ch.27, v.34)

63. If a person gives heed to these teachings he would certainly gain the grace of Lord Siva and attain the state of Selfhood even though he is immersed in the dense darkness of nescience which could not be banished by the glare of a million suns. (Ch.27, v.43)

64. Why waste words? This is the truth in a nutshell. Only those who have earned the Grace of our Lord Siva by long devotional worship will get the rare opportunity of reading this scriptural text which leads to the bliss of peace everlasting in Brahman-Self. (Ch.27, v.44)

65. Only that Jnani who teaches ‘Thou art the thoughtfree, alertly aware, absolutely still, ever blissful, intensely peaceful, unqualified Brahman-Self’, is the true Sat Guru, and others are not. (Ch.28, v.28)

66. Unbroken abidance in the state of alert awareness, unruffled by thoughts, is Self-realization. That is at once the spotless jivan mukti and the magnificent videha mukti. This state is easily attainable only for those who have earned the divine Grace of Siva by deep devotion to Him, and not for others. What is stated here is the import in a nutshell of the message of that charming crest jewel of the Vedas known as the Upanishads. (Ch.29, v.37)

67. Those who give heed to this message and abide in accordance with it will forthwith attain mukti (liberation). They will not suffer from the least particle of affliction; they will enjoy a bliss far greater than the bliss attained from this and all other worlds; they and their environments will be filled with the plenitude of auspicious events. Totally free from all trace of fear, they will never again enter the cycle of births and deaths. They will become the immutable Brahman-Self. All this we swear is the truth beyond doubt. By our Lord Siva, again and again we swear that this is the fundamental truth. (Ch.29, v.40)

69. By the persistent and continued bhavana of ‘I am the Brahman-Self’ all thoughts and feelings of differentiation of Self and non-Self will drop off and permanent abidance in Brahman-Self will be achieved. This bhavana is possible only for those with a keen inquiring mind intent on knowing the Self and not for those who are indifferent about Self-knowledge. (Ch.32, v.18)

70. Ignorance and indifference in regard to the enquiry of the truth about one-self is the store house of nescience and trouble, blocking the view of the Self, and creating in a split second all sorts of illusions and harassment of mental worry. Non-enquiry renders bhavana impossible. (Ch.32, v.19)

71. In short, non-enquiry will steep one for ever in the ocean of samsara (earthly suffering). There is no greater enemy for one than non-enquiry. Therefore, this habit must be overcome in order to fix the mind in the bhavana which leads to abidance in the Self. (Ch.32, v.20)

73. Staying in the company of sadhus (those engaged in the pursuit and enjoyment of the bliss of the Sat-Self) and respectfully questioning the Sat-Guru-Jnani, one should first make oneself clear about the objective to be obtained. This is an important aspect of the enquiry. After thus making sure of the objective, one must firmly abide in that objective of sole Brahman-Self until the Self is unmistakably experienced. (Ch.32, v.22)

74. The conscious introspective concentration of Self enquiry (‘Who am I’?) kills all thoughts and destroys the dense darkness of nescience; it effaces all worry; it illuminates the intellect with the radiance of pure awareness; it wipes out all conceptual confusions; it fixes one in Siva-Self; it transforms a host of impending disasters into auspicious events; and lastly, it destroys the ego-mind utterly with all its afflictions. (Ch.32, v.24)

75. Only by those strong willed persons who make earnest and persistent Self-enquiry will the turbulent mind be controlled and fixed still in the practice of firm bhavana. In due course all thoughts and nescience will disappear, yielding place to the effulgent Awareness-Self of mukti. (Ch.32, v.26)

76. One should relentlessly pursue Self-enquiry until all conceptual forms of creature, world and creator merge and disappear in the pure thought-free, alert Awareness-Self, enabling one to abide in that bhavana of the experience, ‘I am the Brahman-Self’. (Ch.32, v.27)

103. I am verily the Sat-Chit-Ananda-Brahman-Self. I am the eternal undisturbed peace devoid of name and form. I am the flawless integral whole of all existence. Firmly I am settled in my sole Brahman-Self. (Ch.40, v.10)