Rashi on Genesis 8:6/רש"י על בראשית ח׳:ו׳

1מקץ ארבעים יום AT THE END OF FORTY DAYS from when the tops of the mountains were seen.

2את חלון התבה אשר עשה THE WINDOW OF THE ARK WHICH HE HAD MADE — for the light; it does not mean the door of the Ark intended for entry and exit.