knocked the door thrice with greeting

‏‏‎Dr Zakir Naik‎‏ مع ‏סיעדאַ שאַ הוססאַיני‏ و‏‏16‏ آخرين‏‏.

‏15 أكتوبر، 2014‏، الساعة ‏11:30 ص‏ · 

Narrated Anas (ra):
Whenever the Prophet (pbuh) asked permission to enter,
he knocked the door thrice with greeting

Sahih Al-Bukhari, Volume No. 1,
The Book of Knowledge, Hadith No. 94