LXXIII. That Sons are Not to Be Bewailed.
Although the death of sons leaves grief for the heart, yet it is not right either to go forth in black garments, or to bewail them. The Lord prudently says that you must grieve with the mind, not with outward show, which is finished in the week. In the book of Solomon the promises of the Lord concerning the resurrection are forgotten if you would make your sons martyrs, and thus with your voice will bewail them. Are you not ashamed without restraint to lament your sons, like the Gentiles? You tear your face, you beat your breast, you take off your garments; and do you not fear the Lord, whose kingdom you desire to behold? Mourn as it is right, but do not do wrong on their behalf. You therefore are such. What less than Gentiles are you? You do as the crowds that are descended from the diabolical stock. You cry that they are extinct. With what advantage, O false one, you have perished! The father has not led his son with grief to be slain at the altar, nor has the prophet mourned over a deceased son with grief, nor even has a weeping parent. But one devoted to God was hastily dying.
Source: Writings (New Advent)