لَيْسَ مِنَّا مَنْ ضَرَبَ الْخُدُودَ، وَشَقَّ الْجُيُوبَ، وَدَعَا بِدَعْوَى الْجَاهِلِيَّةِ
Not following our way is the one who strikes the cheeks, tears clothing, and calls out with the cries of the age of ignorance.
Source: البخاري ومسلم
ضَرَبَ الْخُدُودَ means striking the cheeks, شَقَّ الْجُيُوبَ tearing the clothing, and دَعَا بِدَعْوَى الْجَاهِلِيَّةِ calling out with cries associated with pre-Islamic customs. The three past-tense verbs describe the conduct being warned against. لَيْسَ مِنَّا is a strong expression of disapproval.
Grief after bereavement is natural. The warning concerns self-harmful and uncontrolled ritualized expressions, not every tear or feeling of sadness. Crying, expressing sorrow, and seeking support may be distinguished from the specific behaviors mentioned in the narration.