Surah 9:26
"Then God sent down His Sakīna on His messenger and on the believers, and He sent down forces you did not see, and punished those who disbelieved – that was the payment of the disbelievers."
This description of battle contains the word Sakīna (also v. 40). Here Allah sends down the Sakīna on the messenger and the “believers” when they are fleeing the battle (v. 25). Allah helps them to prevail over their enemies, the “disbelievers.” See the comment on Sakīna at 2.248.
- from The Quran with Christian Commentary: A Guide to Understanding the Scripture of Islam