Three things which prevent regret
Imam Javad (A.S): whoever had three things, will never regret: 1. refraining from haste 2. Consulting 3.and depending upon God when decision - making (Mesnad Al_Imam Al_Javad, P.247)
Source: alhassanain.com
Other links:
4 Kinds of People
Midnight Prayer
Contentment
Remission
Hard heart
Lying