Abu hurairah said that the Messenger of Allah (May peace be upon him) forbade putting hands on the waist during prayer.

Abu Dawud said; The word Ikhtisar means to put one’s hands on one’s waist.
Sunan Abi Dawud Book 2, Hadith 558
← Previous Hadith Mu’aiqib reported the Prophet (ﷺ) as saying ; Do not remove pebbles while you are praying; if you do it out of sheer necessity, do it only once to smooth the pebbles.

Sunan Abi Dawud Book 2, Hadith 557 Next Hadith → Hilal ibn Yasaf said: I came to ar-Raqqah (a place in Syria). One of my companions said to me: Do you want to see any of the Companions of the Prophet (ﷺ)? I said: A good opportunity. So we went to Wabisah.

I said to my friend: Let us first see his mode of living. He had a cap with two ears stuck (to his head), and wearing a brown silken robe. He was resting on a staff during prayer. We asked him (about resting on the staff) after salutation; He said: Umm Qays daughter of Mihsan said to me that when the Messenger of Allah (ﷺ) became aged and the flesh grew increasingly on him, he took a prop at his place of prayer and rested on it.

Sunan Abi Dawud Book 2, Hadith 559