It is narrated from Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) that a man said to the Prophet (peace and blessings be upon him): "O Messenger of Allah! How can I know when I have done well and when I have done badly?" The Prophet (peace and blessings be upon him) said: "When you hear your neighbours saying that you have done well, then know that you have done well; and when you hear them saying that you have done badly, then know that you have done badly."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 10395