﴿ ثُمَّ أَنزَلَ ٱللَّهُ سَكِينَتَهُۥ عَلَىٰ رَسُولِهِۦ وَعَلَى ٱلْمُؤْمِنِينَ وَأَنزَلَ جُنُودًۭا لَّمْ تَرَوْهَا وَعَذَّبَ ٱلَّذِينَ كَفَرُوا۟ ۚ وَذَٰلِكَ جَزَآءُ ٱلْكَٰفِرِينَ ﴾

“whereupon God bestowed from on high His [gift of] inner peace upon His Apostle and upon the believers, and bestowed [upon you] from on high forces which you could not see, and chastised those who were bent on denying the truth: for such is the recompense of all who deny the truth!”

Please check ayah 9:27 for complete tafsir.