We asked, "Messenger of Allah, this is the greeting, but what is the manner of asking permission to enter?"He replied, "A man should say a tasbeeh, a takbeer, and a tahmeed, clear his throat, and so alert the people of the house."
حدثنا أبو بكر بن أبي شيبة حدثنا عبد الرحيم بن سليمان عن واصل بن السائب عن أبي سورة
قلنا يا رسول الله هذا السلام فما الاستئذان قال يتكلم الرجل تسبيحة وتكبيرة وتحميدة ويتنحنح ويؤذن أهل البيت
No references are available.
[Its chain is daif] Tabarani transmitted it in al-Kabir, 4/178, no. 4065, from the hadith of Ibn Abu Shayba, and it is in al-Musannaf, 8/419, no. 5726, and Busiri graded it daif. Wasil and Abu Surah are both daif, as stated in al-Taqrib and elsewhere.