Reference : Hisn al-Muslim 18

بِسْـمِ اللهِ وَلَجْنـا،
وَبِسْـمِ اللهِ خَـرَجْنـا،
وَعَلـى رَبِّنـا تَوَكّلْـن
(ثم ليسلم على أهله.)
Bismillāhi walajnā, 
wa bismillāhi kharajnā, 
wa `ala Rabbinā tawakkalnā

In the Name of Allah we enter , 
in the Name of Allah we leave , 
and upon our Lord we depend 
[then say As-Salāmu `Alaykum to those present].

Reference:
Abu Dawud 4/325. Muslim {Hadith no. 2018) says that one should mention the 
Name of Allah when entering the home and when beginning to eat; and that 
the devil, hearing this, says: "There is no shelter for us here tonight and 
no food."

Chapter: Remembrance upon entering the home