How many times should one say salam when seeking permission to enter
حَدَّثَنَا زَيْدُ بْنُ أَخْزَمَ، حَدَّثَنَا عَبْدُ الْقَاهِرِ بْنُ شُعَيْبٍ، حَدَّثَنَا هِشَامٌ، عَنْ حُمَيْدِ بْنِ هِلاَلٍ، عَنْ أَبِي بُرْدَةَ بْنِ أَبِي مُوسَى، عَنْ أَبِيهِ، بِهَذِهِ الْقِصَّةِ قَالَ فَقَالَ عُمَرُ لأَبِي مُوسَى إِنِّي لَمْ أَتَّهِمْكَ وَلَكِنَّ الْحَدِيثَ عَنْ رَسُولِ اللَّهِ صلى الله عليه وسلم شَدِيدٌ .
The tradition mentioned above has also been transmitted by Abu Musa in a similar way through a different chain of narrators. This version has: ‘Umar said to Abu Musa : I do not blame you, but the matter of transmitting a tradition from the Messenger of Allah (May peace be upon him) is serious.