Sunan Abi Dawud Book 2, Hadith 402
AbuSalih reported on the authority of some Companions of the Prophet (ﷺ): The Prophet (ﷺ) said to a person: what do you say in prayer?
He replied: I first recite tashahhud (supplication recited in sitting position), and then I say: O Allah, I ask Thee for Paradise, and I seek refuge in Thee from Hell-Fire, but I do not understand your sound and the sound of Mu'adh (what you say or he says in prayer). The Prophet (ﷺ) said: We too go around it (paradise and Hell-fire).
O mu’adh, do not become a trouble , because the aged, the weak, the needy and the traveler pray behind you.
The prophet (ﷺ) said to a youth: My nephew, what do you do in prayer? He replied: I recited fatihat al-katab and I ask Allah for paradise and seek his refuge from hell-fire I do not understand well your sound and the sound of mu’adh. The prophet (ﷺ) said: I and Mu’adh go around both (paradise and Hell-fire), or he said something similar.