They only are true believers who believe in God and His Messenger. When they are with him on some matter of common concern, they should not depart until they have asked him for permission to do so. Those who ask you for such permission are the ones who truly believe in God and His Messenger. When they ask you for permission to attend to some affair of their own, then grant it to whoever you please and seek forgiveness from God for them. God is forgiving and merciful.