Devibhagavatapurana 5.33.40

5.33.40

yatsatyaṃ tadvacaḥ seyaṃ ketakī kathayiṣyati |
ityuktvā preritā tatra brahmaṇā ketakī sphuṭam ||

Brahmâ said:-- “Who will come now as witness from that far off place? This Ketakî flower is the witness; this will give evidence.” Thus saying, Brahmâ requested Ketakî to give evidence; Ketakî soon replied thus to convince Visnu. O Visnu! I was on the head of Mahâdeva; Brahmâ has brought me from there down to this place; you ought not therefore to have any doubt on this point. My word is the evidence; Brahmâ has gone to the other end of the Lingam. Some devotee of S’iva put me on His head and Brahmâ has got me down from there. Hearing thus the words of Ketakî, Visnu was very much astonished and said this:-- “I cannot trust your word; if Mahâ Deva comes and speaks this Himself, then I can trust and take it as a proof.”