Don't let left hand know what right is doing
Matthew 6:1–4 (ASV 1901)
Take heed that ye do not your righteousness before men, to be seen of them: else ye have no reward with your Father who is in heaven.
2When therefore thou doest alms, sound not a trumpet before thee, as the hypocrites do in the synagogues and in the streets, that they may have glory of men. Verily I say unto you, They have received their reward. 3But when thou doest alms, let not thy left hand know what thy right hand doeth: 4that thine alms may be in secret: and thy Father who seeth in secret shall recompense thee.