Matthew 19:3

For every cause] In St. Mark the question simply is, 'Is it lawful for a man to put away his wife?' Jesus was asked to decide the point debated between the school of Hillel, who allowed divorce for every cause, and that of Shammai, who allowed it only for adultery. Rabbi Akiba (a Hillelite) said, 'If a man sees a woman handsomer than his own wife, he may put her away, because it is said, “If she find not favour in his eyes.” The school of Hillel said, 'If the wife cook her husband's food ill, by over-salting or overroasting it, she is to be put away.' On the other hand, Rabbi Jochanan (a Shammaite) said, 'The putting away of a wife is odious.' Both schools agreed that a divorced wife could not be taken back.

Both schools objected to (though perhaps they did not forbid) the divorce of a first wife, with regard to which the dictum of Rabbi Eliezer, 'For the divorcing of a first wife, even the altar itself sheds tears,' was generally approved.