בראשית ח:יב פירוש: רש״י, רד״ק, The Midrash וSiftei Chakhamim

וייחל AND HE STAYED — This has the same meaning as ויחל (Genesis 8:10), only that the latter is the Kal, whereas the word here is the Hithpael: ויחל means “he waited” וייחל “he had patience”.

וייחל עוד, the word is in a passive mode, the root being יחל. If it had been in a hitpael mode, the letter י should have the vowel patach underneath it, but the fact is that it has the vowel kametz.