I often see our brothers touching a person(who is praying a fard prayer)'s back for making jama'at prayer behind him. Even, I do that without knowing it correct or not?
Did our Prophet(PBUH) told us to do like this?
What is the correct way to make congregation with an already praying person?
According to the Hanafi madh'hab, praying Fard behind a leader is only valid if the Imam is also praying Fard. It is, however, permissible to pray Sunnah or Nafil behind a leader praying Fard.
You can never know whether the person is praying a Fard or Sunnat or Nafil salat, as it is by niyat (intention). Hence touching an already praying person and starting one's own Fard salat is risky unless you know for sure that he is also praying Fard.
If I were you, I will not disturb a person who is in prayer. Let him continue his conversation with Allah.
Also, I can't see any proof that Prophet(PBUH) told to do so.
