al-Qurtubi in zijn Tafsir

al-Qurtubi citeert in zijn Tafsir Ibn Abbas:

قال ابن عباس : كانت يهود خيبر تقاتل غطفان فلما التقوا هزمت يهود , فعادت يهود بهذا الدعاء وقالوا : إنا نسألك بحق النبي الأمي الذي وعدتنا أن تخرجه لنا في آخر الزمان إلا تنصرنا عليهم . قال : فكانوا إذا التقوا دعوا بهذا الدعاء فهزموا غطفان , فلما بعث النبي صلى الله عليه وسلم كفروا , فأنزل الله تعالى : " وكانوا من قبل يستفتحون على الذين كفروا " أي بك يا محمد (Source: http://quran.al-islam.com/Tafseer/DispTafsser.asp?nType=1&bm=&nSeg=0&l=arb&nSora=2&nAya=89&taf=KORTOBY&tashkeel=1
"Ibn Abbas said: "The Jews of Khaybar were often at war with the Ghatafān (tribe). When they confronted each other (in battle) the Jews were defeated. They attacked again, offering this prayer, “(O Lord,) we beg You for the sake of the Unlettered Prophet (صلى الله عليه وآله وسلم) about whom You have promised us that you will send him to us at the end of time. Please help us against them.” Ibn ‘Abbās adds: whenever they faced the enemy, they offered this prayer and defeated the Ghatafān (tribe). But when the Prophet (صلى الله عليه وآله وسلم) was sent, they denied (him). So Allah the Exalted revealed the verse: “And before that they themselves had (prayed) for victory (through the mediation of the last Prophet Muhammad and the Book revealed to him) over the disbelievers,” that is, through your mediation, O Muhammad".