once
إِذَا أَكَلَ أَحَدُكُمْ طَعَاماً فَلْيَقُلْ بِسْمِ اللَّهِ، فَإِنْ نَسِيَ فِي أَوَّلِهِ فَلْيَقُلْ بسمِ اللَّهِ فِي أَوَّلِهِ وَآخِرِهِ
Edition transliteration
When you are about to eat, you should say:(Bismil-lah.)and if you forget to say it before starting, then you should say (when you remember):Bismil-lahi fee awwalihi wa-akhirih.
Meaning
When you are about to eat, you should say:(Bismil-lah.)and if you forget to say it before starting, then you should say (when you remember):In the name of Allah in it’s beginning and end.
Source and references
Hisn al-Muslim, entry 178.The reference is copied from the edition; separate editorial verification is not complete yet.
Source edition: Fortress of the Muslim. Open source ↗