Fiqh-us-Sunnah Volume 1, Purification and Prayer, Fiqh 1.023.

This applies to both men and women. ‘Amr ibn Shu’aib related on the authority of his father from his grandfather that the Prophet said, “Do not pluck the grey hairs as they are a Muslim’s light. Never a Muslim grows grey in Islam except that Allah writes for him, due to that, a good deed. And he raises him a degree. And he erases for him, due to that, one of his sins.” (Related by Ahmad, Abu Dawud, at-Tirmizhi, an-Nasa’i and Ibn Majah.) And Anas said, “We used to hate that a man should pluck out his white hairs from his head or beard.” (Related by Muslim.)