Shaykh Abdul-Muhsin al-Abbaad was asked:
Some of the brothers make themselves a sutrah for the one who came late to the prayer n terms that they sit in front of him believing that there is reward in that. So what is the ruling on it?
“As for him being a sutrah, then there is no problem in that. As for the one sitting as a sutrah, whether he will have a reward or not? He will have a reward because he is doing good to him [the one praying]. And Allah knows best. Yes. Verily actions depend on intentions”.
[Sharh Ibn Majah no. 74]
Faisal Ibn Abdul Qaadir Ibn Hassan