Hadith 17:930
Abu Bakr narrated to us, he said: Waki’ narrated to us, from Sufyan, from Mansur, from Talha, from al-Hudhayl ibn Shurahbil, that Sa’d asked for permission to enter upon the Prophet, may Allah bless him and grant him peace, and he put his head in. The Messenger of Allah, may Allah bless him and grant him peace, said: "Permission was only made because of the sight."
حدثنا أبو بكر قال حدثنا وكيع عن سفيان عن منصور عن طلحة عن [ الهزيل ] بن شرحبيل أن سعدا استأذن على النبي صلى الله عليه وسلم فأدخل رأسه فقال رسول الله صلى الله عليه وسلم إنما جعل الاستئذان من أجل النظر