﴿ قَدْ فَرَضَ ٱللَّهُ لَكُمْ تَحِلَّةَ أَيْمَٰنِكُمْ ۚ وَٱللَّهُ مَوْلَىٰكُمْ ۖ وَهُوَ ٱلْعَلِيمُ ٱلْحَكِيمُ ﴾

“God has already enjoined upon you [O believers] the breaking and expiation of [such of] your oaths [as may run counter to what is right and just]: for, God is your Lord Supreme, and He alone is all-knowing, truly wise.”

(Allah hath made lawful for you (Muslims) absolution from your oaths (of such a kind)) and so the Prophet (pbuh) absolved himself from his oath and married Maria the Copt, (and Allah is your Protector) and Helper. (He is the Knower) He knows that you forbade yourself Maria the Copt, (the Wise) in that which He enjoined about the expiation of oaths.