When anyone of you begins eating, say:
178. Bismillaah.
With the Name of Allah.
And if you forget then, when you remember, say:
Bismillaahifee 'awwalihi wa 'aakhirihi.
With the Name of Allah, in the beginning and in the end.
Reference: Abu Dawud 3/347, At-Tirmithi 4/288. See Al- Albani's Sahih At-Tirmithi 2/167.
Whomever Allah has given food, should say:
179. Allaahumma baarik lanaafeehi wa 'at'imnaa khayranminhu.
O Allah, bless us in it and provide us with better than it.
Whomever Allah has given milk to drink, should say :
Allaahumma baarik lanaa feehi wa zidnaa minhu.
O Allah , bless us in it and give us more of it.
Reference: At-Tirmithi 5/506. See also Al-Albani, Sahih At-Tirmithi 3/158.