I was reading the Van Buitenen trans. of Mahabharata, particularly this passage:


…One should then [after Gṛdhravaṭa] go to Mount Udyanta, which is noisy with song […] There too is the famous Gate-of-the-Womb: by approaching it a man is freed from any miscegenation.  If one dwells for both the dark and the light at Gayā, he doubtlessly purifies his lineage to seven generations. Many sons should be wished for, if one goes to Gayā alone, or sacrifices with the Horses Sacrifice, or sets free a dark bull. (3.82.80-85)