Niyar bin Mukram reported,

When the verse was revealed, "Alif Lam Mim. The Romans have been defeated in the nearest land, but they, after their defeat, will be victorious within a few years" [Rum 30:1–4], the Persians on the day this verse was revealed were dominant over the Romans. The Muslims wished for the Romans to prevail over the Persians because the Romans, like themselves, were people of a revealed scripture. Concerning this, Allah Most High said, "And on that day the believers will rejoice in the victory of Allah. He grants victory to whom He wills, and He is the Mighty, the Merciful" [Rum 30:4–5].Quraysh, on the other hand, wished for the Persians to prevail, since they, like the Persians, were neither people of scripture nor believers in resurrection. When Allah Most High revealed this verse, Abu Bakr al-Siddiq went out calling throughout the districts of Mecca, "Alif Lam Mim. The Romans have been defeated in the nearest land, but they, after their defeat, will be victorious within a few years" [Rum 30:1–4].Some men of Quraysh said to Abu Bakr, "Then let this be settled between us and you. Your companion claims that the Romans will defeat the Persians within a few years. Will you not wager with us on that?"Abu Bakr replied, "Yes." This was before wagering had been forbidden. So Abu Bakr and the polytheists made their wager and agreed on the stakes.They said to Abu Bakr, "How many years will you set for 'a few'? It is between three and nine years. Name an intermediate term between us that we can settle on."So they agreed on six years between them. The six years passed before the Romans were victorious, and the polytheists took the stake from Abu Bakr. When the seventh year began, the Romans prevailed over the Persians. The Muslims faulted Abu Bakr for naming six years, since Allah Most High had said "within a few years." At that point, many people embraced Islam.

حدثنا محمد بن إسمعيل حدثنا إسمعيل بن أبي أويس حدثني ابن أبي الزناد عن أبي الزناد عن عروة بن الزبير

عن نيار بن مكرم الأسلمي قال

لما نزلت {الم غلبت الروم في أدنى الأرض وهم من بعد غلبهم سيغلبون في بضع سنين} فكانت فارس يوم نزلت هذه الآية قاهرين للروم وكان المسلمون يحبون ظهور الروم عليهم لأنهم وإياهم أهل كتاب وفي ذلك قول الله تعالى {ويومئذ يفرح المؤمنون بنصر الله ينصر من يشاء وهو العزيز الرحيم} وكانت قريش تحب ظهور فارس لأنهم وإياهم ليسوا بأهل كتاب ولا إيمان ببعث فلما أنزل الله تعالى هذه الآية خرج أبو بكر الصديق رضي الله عنه يصيح في نواحي مكة {الم غلبت الروم في أدنى الأرض وهم من بعد غلبهم سيغلبون في بضع سنين} قال ناس من قريش لأبي بكر فذلك بيننا وبينكم زعم صاحبك أن الروم ستغلب فارس في بضع سنين أفلا نراهنك على ذلك قال بلى وذلك قبل تحريم الرهان فارتهن أبو بكر والمشركون وتواضعوا الرهان وقالوا لأبي بكر كم تجعل البضع ثلاث سنين إلى تسع سنين فسم بيننا وبينك وسطا تنتهي إليه قال فسموا بينهم ست سنين قال فمضت الست سنين قبل أن يظهروا فأخذ المشركون رهن أبي بكر فلما دخلت السنة السابعة ظهرت الروم على فارس فعاب المسلمون على أبي بكر تسمية ست سنين لأن الله تعالى قال في بضع سنين وأسلم عند ذلك ناس كثير