We do not send a messenger except to be obeyed by God's leave. Had they come to you when they had wronged themselves and sought God's forgiveness, and the messenger sought forgiveness for them, they would have then found God to be Pardoning, Compassionate.
Translation endnotes
[4:64] The divine message delivered by the messenger should be acknowledged and obeyed. Additionally, when the messenger is alive as an elected leader, his instructions and judgment should be obeyed, as long as his instructions are in conformity with known facts (60:12). The live messenger, as a fallible human, must consult people around him (3:159). The messenger of God cannot issue rules in the name of God, and like everyone else he is also responsible for following God's judgment (5:48-50). We may pray for the forgiveness of our friends and subordinates if their mistake involves us. Also, see 12:98.