In the Srimad Bhagavatam, 10th Canto, XX chapter, we read of Krishna and Arjuna going to see Lord Mahavisnu in order to help Arjuna keep his vow to retrieve the nine children of a Brahmana, children who died immediately after their births. Lord Mahavisnu says this to Lord Krishna when the Lord comes to Him (SB10.89.58): “I brought the Brahmanas sons here because I wanted to see the two of you, My expansions, who have descended to the earth to save the principles of religion?.”