It was narrated that Abu Ayyub Ansari said:
"We said: 'O Messenger of Allah(ﷺ), (we know) this (greeting of) Salam, but what does seeking permission to enter mean?' He said: 'It means a man saying SubhanAllah, and Allahu Akbar and Al Hamdulillah, and clearing his throat, announcing his arrival to the people in the house."
It was narrated from Abu Saeed Khudri that Abu Musa asked permission to enter upon 'Umar three times, and he did not give him permission, so he went away.'Umar sent word to him saying:
"Why did you go back?" He said: "I…
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا أَبُو بَكْرِ بْنُ عَيَّاشٍ، عَنْ مُغِيرَةَ، عَنِ الْحَارِثِ، عَنْ عَبْدِ اللَّهِ بْنِ نُجَىٍّ، عَنْ عَلِيٍّ، قَالَ كَانَ لِي مِنْ رَسُولِ اللَّهِ ـ صلى الله عليه وسلم ـ مُدْخَلاَنِ مُدْخَلٌ بِاللَّيْلِ وَمُدْخَلٌ بِالنَّهَارِ فَكُنْتُ إِذَا أَتَيْتُهُ وَهُوَ يُصَلِّي يَتَنَحْنَحُ لِي .
It was narrated that Ali said:
"I had two times of visiting the Messenger of Allah(ﷺ), at night and during the day. If I came to him when he was praying, he would clear his throat (to let me know he was praying)."
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا وَكِيعٌ، عَنْ شُعْبَةَ، عَنْ مُحَمَّدِ بْنِ الْمُنْكَدِرِ، عَنْ جَابِرٍ، قَالَ اسْتَأْذَنْتُ عَلَى النَّبِيِّ ـ صلى الله عليه وسلم ـ فَقَالَ " مَنْ هَذَا " . فَقُلْتُ أَنَا فَقَالَ النَّبِيُّ ـ صلى الله عليه وسلم ـ " أَنَا أَنَا " .
It was narrated that Jabir said:
"I asked the Prophet(ﷺ) for permission to enter, and he said: 'Who is that?' I said: 'Me'. The Prophet(ﷺ) said " Me, me?!"