Garudapurana 2.5.22

2.5.22

yadvā yasmindine dānaṃ tasmiṃstaddinasaṃkhyayā /
daśāhe 'ñjalayaḥ pakṣinpañcāśadantime //

or the offering on any day should match the number of that day. / Over ten days, O bird, fifty handfuls of water [are offered] at the end;