I have an app called Divine Pearls which recommends some dhikr to do after each namaz. For example:
"Imam Jafar Sadiq is reported as saying: Anyone who implores Almighty Allah's forgiveness seventy times after Asr prayer will have 700 of his sins forgiven"

What is the source for hadith like this and where can I find more regarding what dhikr leads to what reward

by

http://duas.org/