" about the hardship of the prostration on them, when they were so spread out, so he said: 'Use your knees.'"
Jami` at-Tirmidhi Book 2, Hadith 138
← Previous Hadith (Another chain) which is similar.

Jami` at-Tirmidhi Book 2, Hadith 137 Next Hadith → Allah's Messenger performing Salat. When he was in an odd number of his Salat, he would not get up until he had sat completely.

Jami` at-Tirmidhi Book 2, Hadith 139