Sayyiduna ‘Umar bin ‘Absah (may Allah be pleased with him) narrates that the Noble Prophet (peace and blessings be upon him) said: Whoever grows old in the way of Allah, then this whiteness of old age will become light for him on the Day of Resurrection.
Benefits: … "Fi Sabilillah" (in the path of Allah): If we consider customary usage, its meaning will be jihad, i.e., whoever began jihad from the age of black hair and continued this action until the hair turned white. However, it is better to interpret it as referring to every righteous deed, because in the ahadith, the white hair of a believer has been described as light (nur) for him, whereas the virtue of jihad is not dependent on white hair; it is virtuous even without it. And Allah knows best. Whether the hair itself will become light or light will be granted on account of it.