בראשית ח:ח פירוש: רש״י, ספורנו, The Midrash וSiftei Chakhamim

וישלח את היונה AND HE SENT FORTH A DOVE at the end of seven days, for it is written, (Genesis 8:10) “And he stayed yet other seven days” — from this statement you may infer that after the first occasion, also, he waited seven days.

וישלח את היונה, all of the seven pairs of pigeons [based on the latter ה in front of the word יונה. Ed.]