قَوْلاً سَدِيداً
(speak (always) the truth.) meaning, to speak in a straightforward manner, with no crookedness or distortion. He promises them that if they do that, He will reward them by making their deeds righteous, i.e., enabling them to do righteous deeds, and He will forgive them their past sins. With regard to whatever sins they may commit in the future, He will inspire them to repent from them. Then He says: