Is it permissible to weep and mourn for the deceased?

It is normal for a person to feel sorrow, grief, and sadness due to death. There is no harm in expressing this pain by weeping quietly and shedding tears. The Prophet Muhammad (peace be upon him) also wept silently with tears in his eyes at the death of his son Ibrahim, his daughter, and his grandchild. (Bukhari, Janaiz, 32, 43 [1284, 1303]) However, he also stated that it is not appropriate to object to Allah’s decree or to mourn by tearing one’s collar and clothes as was done in the Age of Ignorance. Indeed, the Prophet’s (peace be upon him) words after the death of his young son Ibrahim, “…The eyes shed tears, the heart grieves, but we do not say anything except what pleases our Lord.” (Bukhari, Janaiz, 43 [1303]), serve as an example for believers in this matter.

Source: T.C. Diyanet İşleri Başkanlığı, Din İşleri Yüksek Kurulu