It is narrated from Sayyiduna Abdullah (may Allah be pleased with him) that he said: "If the Messenger of Allah (peace and blessings be upon him) found (in the prayer row) a man's shoulder out of line with his companion's shoulder, he would straighten it (by bringing it level) and say: 'Do not differ (in the rows), or your hearts will differ.'"
Imam al-Tabarani (may Allah have mercy on him) said: "No one narrated this hadith from Mis'ar (may Allah have mercy on him) except Hafs bin Ghiyath and Khalid bin Yazid al-Qasri; his son Umar bin Hafs is alone in narrating it from Hafs, while Hisham bin Khalid is alone in narrating it from Khalid bin Yazid."
Hadith Referenceالمعجم الأوسط / باب الميم / 6658
Hadith Takhrij«أخرجه الطبراني فى «الكبير» برقم: 10261»