Professor Kashi Nath Upadhyaya in his "Early Buddhism and Bhagavadgita" page 16-19 says
Evidences for the existence of the MB after the 1st century A.D. are too numerous and too well known to be recounted here. We may, therefore, begin with the testimony of the works of Asvaghosa, a Mahayana Buddhist of the 1st century A.D. In his ‘Buddhacarita’ as well as ‘Saundaiananda’ he evidently makes use of the episodes of the MB. Again in his *Bajra Suci’, some verses of the ‘Sraddha Mahatmya’ portion of the Harivamsa as well of other portions of the MB are quoted. This indicates that by his time the MB with its appendix, Harivamsha must have been well known. Still earlier references are to be found in the ‘Grhya-Sutra’ of Asvalayana as well as in the Dharma-Sutra and Grhya-Sutra of Baudhayana. Asvalayana makes clear mention of the Bharata as well as the in his Grhya-Sutra 3.4.4. In Baudhayana’s Dharma Sutra 2.2.26 a verse occurs which is found in the MB Adi.78.10. His Grhya Sutra (1.22.8 ) clearly mentions the name of the ‘Visnu-sahasra-nama’ which is a portion of the MB and further in Sutra 2.22.9, an important verse of the Gita 9.26 is clearly quoted. The date assigned to Baudhayana by Dr. Buhler is not later than 400 B.C. By this time the MB seems to have been popular along with Gita, the verses of which are quoted by Baudhayana in high reverence.From the clear mention of the two names, the Bharata and the Mahabharata in the Grhya Sutra of Asvalayana, it is reasonable to infer that the MB was developed from the Bharata, perhaps, not long before Asvalayana, for after a considerable lapse of time, the name Bharata was almost forgotten. As the Gita is not considered as a later addition of the MB , it is reasonable to believe that it might have been composed sometime between the 5th and the 4th century B.G. We shall, however, further examine this question and see whether this date is confirmed on other independent grounds
Where can I find these 3 verses from Grhya Sutra :
Baudhayana Grhya Sutra 1.22.0
Asvalayana Grhya-Sutra 3.4.4
Baudhayana Grhya Sutra 2.22.9
And you give me English translation of these verses.