The Book of Faith
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا حَفْصٌ، عَنْ عَبْدِ الْمَلِكِ، عَنْ عَطَاءٍ، عَنِ ابْنِ عَبَّاسٍ، قَالَ رَآهُ بِقَلْبِهِ .It is narrated on the authority of Ibn 'Abbas that he (the Holy Prophet) saw (Allah) with, his heart
From Sahih Muslim, whose reports the scholars accept as authentic.