Hadith 227

When someone enters a house which is not lived in, he should say, 'Peace be upon the righteous slaves of Allah.'" السَّلاَمُ عَلَيْنَا وَعَلَى عِبَادِ اللهِ الصَّالِحِينَ‏.‏

‘Abdullah Ibn ‘Umar (رضي الله عنه)Al-Adab Al-Mufrad 1055Adab & Virtues of Asking Permission