The Prophet (ﷺ) forbade praying with one's hands on one's waist.
Sunan an-Nasa'i Book 11, Hadith 15
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"I said: 'I am going to watch how the Messenger of Allah (ﷺ) prays.' So I watched him and he stood and said the takbir, and raised his hands until they were in the level with his ears, then he placed his right hand over his left hand, wrist and lower forearm. When he wanted to bow he raised his hands likewise. Then he prostrated and placed his hands in level with his ears. Then he sat up and placed his left leg under him; he put his left hand on his left thigh and knee, and he put the edge of his right elbow on his right thigh, then he held two of his fingers together and made a circle, and raised his forefinger, and I saw him moving it and supplicating with it."
Sunan an-Nasa'i Book 11, Hadith 14 Next Hadith → "I prayed beside Ibn Umar and put my hand on my waist, and he did this to me-knocked it with his hand. When I had finished praying I said to a man: 'Who is this?' He said: "Abdullah bin Umar.' I said: 'O Abu Abdur-Rahman, why are you angry with me?' He said: 'This is the posture of crucifixion, and the Mesenger of Allah (ﷺ) forbade us to do this.'"
Sunan an-Nasa'i Book 11, Hadith 16
Sunan an-Nasa'i Book 11, Hadith 14 Next Hadith → "I prayed beside Ibn Umar and put my hand on my waist, and he did this to me-knocked it with his hand. When I had finished praying I said to a man: 'Who is this?' He said: "Abdullah bin Umar.' I said: 'O Abu Abdur-Rahman, why are you angry with me?' He said: 'This is the posture of crucifixion, and the Mesenger of Allah (ﷺ) forbade us to do this.'"
Sunan an-Nasa'i Book 11, Hadith 16