Hadith 39, 40 Hadith an-Nawawi
On the authority of Ibn Abbas (may Allah be pleased with him), that the Messenger of Allah (peace and blessings of Allah be upon him) said:
Verily Allah has pardoned [or been lenient with] for me my ummah: their mistakes, their forgetfulness, and that which they have been forced to do under duress.

A hasan hadeeth related by Ibn Majah, and al-Bayhaqee and others.
عَنْ ابْنِ عَبَّاسٍ رَضِيَ اللَّهُ عَنْهُمَا أَنَّ رَسُولَ اللَّهِ صلى الله عليه و سلم قَالَ: "إنَّ اللَّهَ تَجَاوَزَ لِي عَنْ أُمَّتِي الْخَطَأَ وَالنِّسْيَانَ وَمَا اسْتُكْرِهُوا عَلَيْهِ" . 
حَدِيثٌ حَسَنٌ، رَوَاهُ ابْنُ مَاجَهْ [رقم:2045]، وَالْبَيْهَقِيّ ["السنن" 7 ].