Sayyiduna Abu Mas'ud (may Allah be pleased with him) narrates: The Prophet (peace and blessings of Allah be upon him) used to pass his hand over our shoulders before starting the prayer and would say: "Keep (your rows) straight and do not differ among yourselves, otherwise your hearts will differ. Let those among you who are wise and experienced stand close to me, then those who are next to them in rank, and then those who are next to them in rank." Sayyiduna Abu Mas'ud (may Allah be pleased with him) says: "Today, there are severe differences among you."