Saeed bin Jubayr reported,

Ibn Abbas said regarding the verse "Alif Lam Mim. The Romans have been defeated" [Rum 30:1–2], "It can be read as 'have been defeated' and as 'have been victorious.'"He explained, "The idolaters wanted Persia to prevail over the Romans, since the Persians were idol worshippers, while the Muslims wanted the Romans to prevail over Persia, since they were people of a scripture. The Muslims mentioned this to Abu Bakr, and Abu Bakr mentioned it to the Messenger of Allah ﷺ.The Messenger of Allah ﷺ said, "The Romans will certainly be victorious."Abu Bakr reported this to the idolaters, and they said, "Set a term between us and you. If we prevail, we get such and such, and if you prevail, you get such and such."So he set a term of five years, and the Romans did not prevail. Abu Bakr mentioned this to the Prophet ﷺ, who said, "Why did you not make it less than that?"The narrator said, "I think he said, 'less than ten.'"Saeed bin Jubayr said, "The word bid refers to anything under ten."Then afterward the Romans did prevail. Ibn Abbas said, "That is the meaning of His words, 'Alif Lam Mim. The Romans have been defeated' [Rum 30:1–2], up to His words, 'And on that day the believers will rejoice' [Rum 30:4]." He said, "They will rejoice 'at the victory granted by Allah' [Rum 30:5]."

حدثنا معاوية بن عمرو حدثنا أبو إسحاق عن سفيان عن حبيب بن أبي عمرة

عن سعيد بن جبير

عن ابن عباس في قوله {الم غلبت الروم} قال غلبت وغلبت قال كان المشركون يحبون أن تظهر فارس على الروم لأنهم أهل أوثان وكان المسلمون يحبون أن تظهر الروم على فارس لأنهم أهل كتاب فذكروه لأبي بكر فذكره أبو بكر لرسول الله ﷺ فقال رسول الله ﷺ أما إنهم سيغلبون قال فذكره أبو بكر لهم فقالوا اجعل بيننا وبينك أجلا فإن ظهرنا كان لنا كذا وكذا وإن ظهرتم كان لكم كذا وكذا فجعل أجلا خمس سنين فلم يظهروا فذكر ذلك أبو بكر للنبي ﷺ فقال ألا جعلتها إلى دون قال أراه قال العشر قال قال سعيد بن جبير البضع ما دون العشر ثم ظهرت الروم بعد قال فذلك قوله {الم غلبت الروم} إلى قوله {ويومئذ يفرح المؤمنون} قال يفرحون {بنصر الله}