A'isha, the wife of Allah's Apostle ( صلی اللہ علیہ وسلم ) , reported that Allah's Messenger ( صلی اللہ علیہ وسلم ) used to say: Observe moderation (in doing deeds), and if you fail to observe it perfectly, try to do as much as you can do (to live up to this ideal of moderation) and be happy for none would be able to get into Paradise because of his deeds alone. They (the Companions of the Holy Prophet) said: Allah's Messenger, not even thou? Thereupon he said: Not even I, but that Allah wraps me in His Mercy, and bear this in mind that the deed loved most by Allah is one which is done constantly even though it is insignificant.

This hadith has been narrated on the authority of Musa bin 'Uqba with the same chain of transmitters and he did not make a mention of: "Be happy".