The Great Excellence of the Dhikr After Eating
Anas and Mu’adh (may Allaah be pleased with them) said: the Messenger of Allaah (sallahAllaahu alayhi wasallam) said: “Whoever eats some food and then says:
الْحَمْدُ لِلَّهِ الَّذِي أَطْعَمَنِي هَذَا وَرَزَقَنِيهِ مِنْ غَيْرِ حَوْلٍ مِنِّي وَلَا قُوَّةٍ
All perfect praise is for Allaah who fed me this, and provided it to me, without any strength of change or might from me, [Whoever says this] all his past sins are forgiven.” 
Wallaahi this is a great excellence, and another manifestation of the great mercy of Ar-Rahmaan. Can we even count the times we eat!!?
The Link above is the audio recitation of this dhikr, we should try to avoid transliterations as much as possible, so that it can be pronounced properly and so that it can be memorized inshaAllaah.
You will find that in the audio the dhikr is repeated three times, this is for learning purposes; it doesn’t mean you say the dhikr three times, I repeated it three times for easier learning inshaAllaah.
Note: For this type of dhikr and all other adhkaar to be beneficial they have to have an effect on the heart, and that we just don’t say them by the tongue, rather we really believe in it and then proclaim it.
1. Sunan at-Tirmidhee, Chapter: What is said after eating, Graded as Hasan by Shaykh Al-Albaani