Arabic text
عن أبي موسى الأشعري رضي الله عنه مرفوعاً: «إذا كان يومُ القيامة دفع اللهُ إلى كل مسلم يهوديا أو نصرانيا، فيقول: هذا فِكَاكُكَ من النار». وفي رواية: «يجيء يومَ القيامة ناسٌ من المسلمين بذنوبٍ أمثالِ الجبال يغفرها الله لهم».
Translation
Abu Mūsa al-Ash‘ari (may Allah be pleased with him) reported that the Prophet (may Allah's peace and blessings be upon him) said: "On the Day of Resurrection, Allah will deliver to every Muslim a Jew or a Christian and say: 'This is your ransom from Hellfire.'" Another narration reads: "On the Day of Resurrection, there will come people from the Muslims with sins as huge as mountains, and Allah will forgive them."
Explanation
The meaning of this Hadīth is explained in the report of Abu Hurayrah (may Allah be pleased with him) which reads: "Each person has an abode in Paradise and an abode in Hell. If the believer enters Paradise, the disbeliever in Hell will take his place in it, because he deserves that due to his disbelief." "This is your ransom from the Hellfire" means that you were exposed to the risk of entering Hell, but this is your ransom. This is because Allah, the Almighty, decreed a number of inmates to enter Hell and fill it. When the disbelievers enter it because of their disbelief and sins, they will become like ransom for the Muslims. Allah knows best.
Source: HadeethEnc.com