Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) said: "Indeed Allah, the Mighty and Majestic, looked into the hearts of His servants and found the heart of Muhammad (peace and blessings be upon him) to be the best of the hearts of the servants." Then the narrator mentioned the rest of the hadith like the hadith of Asim.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 8561