"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)."
كَانَ لِي مِنْ رَسُولِ اللَّهِ ﷺ مُدْخَلاَنِ مُدْخَلٌ بِاللَّيْلِ وَمُدْخَلٌ بِالنَّهَارِ فَكُنْتُ إِذَا أَتَيْتُهُ وَهُوَ يُصَلِّي يَتَنَحْنَحُ لِي
"I had two times when I would enter upon the Messenger of Allah ﷺ, one at night and one during the day. When I entered at night he would clear his throat (to tell me to come in)."
عَلِيٌّ كَانَ لِي مِنْ رَسُولِ اللَّهِ ﷺ مَدْخَلاَنِ مَدْخَلٌ بِاللَّيْلِ وَمَدْخَلٌ بِالنَّهَارِ فَكُنْتُ إِذَا دَخَلْتُ بِاللَّيْلِ تَنَحْنَحَ لِي
"I had two times when I would enter upon the Messenger of Allah ﷺ, one at night and one during the day. When I entered at night he would clear his throat (to tell me to come in)." (Using translation from Nasāʾī 1212)
قَالَ عَلِيٌّ كَانَ لِي مِنَ النَّبِيِّ ﷺ مَدْخَلَانِ مَدْخَلٌ بِاللَّيْلِ وَمَدْخَلٌ بِالنَّهَارِ فَكُنْتُ إِذَا دَخَلْتُ بِاللَّيْلِ تَنَحْنَحَ لِي