Is it from the Sunnah, when performing the funeral prayer, to multiply the rows, or should the worshippers remain in a single row if their number exceeds one hundred?

It is recommended in the funeral prayer that the rows be three, regardless of whether the number of worshippers is few or many. This is based on the hadith (definition) of Jabir, may Allah be pleased with him, that the Prophet, may Allah's prayers and peace be upon him, prayed over the Negus, and the rows were formed. It is also based on the saying of Malik ibn Hubayrah, may Allah be pleased with him: "There is no Muslim who dies, and three rows of Muslims pray over him, but that [Paradise] becomes obligatory for him." The jurists of the madhhabs have explicitly stated the desirability of this, and having three rows is better than one long row. If the Imam prays with a single row, the prayer is valid, and there should be no disagreement with him.