Bhagavatapurana 10.85.36

10.85.36

tayoḥ samānīya varāsanaṃ mudā niviṣṭayos tatra mahātmanos tayoḥ /
dadhāra pādāv avanijya taj jalaṃ sa-vṛnda ā-brahma punad yad ambu ha //

36. He offered them both excellent seats and when they gladly accepted them he washed the feet of those two glorious Rulers and sprinkled his head, as also all the members of the family, with that water which purifies the whole world from Brahma downwards.