It behoves somebody to do something
Definition 1 of 1
Pro Tip 1/3Moral Obligation
Use this phrase to express moral responsibility rather than legal requirement. 
Having witnessed the accident, it behoves you to testify truthfully.
Pro Tip 2/3Formal Contexts
It's formal and best used in serious, professional, or ceremonial discourse. 
It behoves the committee to consider all members' opinions before deciding.
Pro Tip 3/3Personal Integrity
Suggests action is consistent with someone's character or the expectations placed upon them. 
As a leader, it behoves you to act with honesty and transparency.