>>12834567you are flithy ignorant idiot. We use the phrase "Peace be upon him" as sign of great respect and honor and because Alah commanded us to do so
(إِنَّ اللَّهَ وَمَلائِكَتَهُ يُصَلُّونَ عَلَى النَّبِيِّ يَا أَيُّهَا الَّذِينَ آمَنُوا صَلُّوا عَلَيْهِ وَسَلِّمُوا تَسْلِيمًا) الأحزاب / 56 .
trasnlaation
Indeed, Allah showers His blessings upon the Prophet, and His angels pray for him. O believers! Invoke Allah’s blessings upon him, and salute him with worthy greetings of peace
Also to grant us درجات "The Messenger of Allah صلى الله عليه وسلمﷺ) said: "Whoever sends salah upon me once, Allah (SWT) will send salah upon him tenfold, and will erase ten sins from him, and will raise him ten degrees in status."
. We say or write the phrase to get Allah's blessings for prophet/messenger and we know that the prophet (PBUH) is in Jannah unlike Christisans who will burn in hell for eternity for their blashphemy and kufr.