Verse 18

لَّقَدْ رَضِىَ ٱللَّهُ عَنِ ٱلْمُؤْمِنِينَ إِذْ يُبَايِعُونَكَ تَحْتَ ٱلشَّجَرَةِ فَعَلِمَ مَا فِى قُلُوبِهِمْ فَأَنزَلَ ٱلسَّكِينَةَ عَلَيْهِمْ وَأَثَـٰبَهُمْ فَتْحًا قَرِيبًا

Indeed, God is pleased with the faithful who pledged allegiance to you under the tree. He knew what was in their hearts, therefore, He sent down upon them tranquility; and He rewarded them with an immediate victory;