Bara' reported:
When the Ansar performed the Pilgrimage, they did not enter their houses but from behind. A person from the Ansar came and he began to enter from his door but it was said to him (why he was doing something in contravention to the common practice of coming to the houses from behind). Then this verse was revealed." Piety is not that you come to the doors from behind" (ii. 189).
Reference: Sahih Muslim 3026
In-book reference: Book 56, Hadith 27
USC-MSA web (English) reference(deprecated numbering scheme): Book 43, Hadith 7177