The Prophet (peace and blessings of Allah be upon him) organized the matter of congregational prayer. He taught us the qualities of the Imam, then who should stand behind him from among those with knowledge who memorize the Quran and with sound minds, then how the rows should be arranged, how people should be gentle with one another, then how children and women should be in the back rows, and other matters.This Hadith is part of another Hadith, in which he said: "Let those among you who are mature and wise stand close to me," meaning: let those with sound minds and forbearance stand behind me in prayer, "then those who come after them, then those who come after them," meaning: then let the most excellent, then the next most excellent arrange themselves behind them. Then he (peace and blessings of Allah be upon him) said: "And do not differ, lest your hearts differ," meaning: be harmonious and gentle in your standing next to each other in prayer, for disagreement in this situation becomes a cause for the differing of hearts. Then he (peace and blessings of Allah be upon him) said: "And beware of the clamor of the markets," meaning: beware of raising voices in prayer and mosques, and speaking without benefit, as happens in the markets. Do not let thinking about such matters distract you from humility in prayer. It is possible that this is a prohibition against mixing in mosques and in prayer rows, so that those with sound minds and the elderly should not mix with the young and women as in the markets.This Hadith contains a prohibition against disagreement among people in prayer and in standing in rows. It also contains a warning against raising one's voice and mixing in prayer and mosques, as is often done in the markets..