Sahih Muslim Book 4, Hadith Number 881.

Chapter : The command to observe prayer with tranquillity and calmness and forbiddance of making gesture with hands and lifting them while pronouncing salutation, and the completing of first rows and joining together well in them.

Abu Huraira said: The best rows for men are the first rows, and the worst ones the last ones, and the best rows for women are the last ones and the worst ones for them are the first ones.