Hadith 1169
Lady Aisha (may Allah be pleased with her) narrates that when the Messenger of Allah (peace be upon him) performed a prayer, he would do so regularly, and when he (peace be upon him) missed the Tahajjud prayer due to sleep or became ill, he would perform twelve rak‘ahs during the day.
Hadith 1170
Lady Aisha (may Allah be pleased with her) narrates that when the Messenger of Allah (peace and blessings be upon him) performed any prayer, he liked to be consistent and regular in it. And whenever sleep, illness, or any difficulty prevented him (peace and blessings be upon him) from performing the Tahajjud prayer, he (peace and blessings be upon him) would offer twelve rak‘ahs during the day. This is the narration of Yahya bin Sa‘eed.