Sheikh Abdul Azeez bin Baaz was asked;
Does the rank (row) begin from the right of the Imaam or his left? Is it necessary to have the same number of people on the right and left of the Imaam? I ask this because we know that many of the Imaams command the people to make the rows even on each side these days.
The Sheikh then replied;
The rank begins in the middle of the rank (row) right behind the Imaam. The right of ever row is more virtuous then the left. That which is obligatory, is to not start a new rank (row) until the one before it is complete, and there is no problem for the right side to have more people on it then the left side. Therefore, it is not necessary to make the number of people on both sides equal in number. Rather the command to do this is in contradiction of the Sunnah.
It is important though to remember that the second rank (row) should not be started until the first one is completely filled. The third, just like it, should not be started until the second is completed, and so on. This is because we find that the Prophet (صلى الله عليه و سلم) commanded the people with this.
[Taken from Majmoo’ al Fataawah of Sheikh Bin Baaz]
[Translated by Abu Abdillah Abdul Lateef]