It was narrated from Sa’ib bin Yazid, if Allah wills, that the Prophet (ﷺ) wore two coats of mail on the Day of Uhud, one over the other.
Related hadith on this topic
Explanation & Benefits
Shaykh Umar Farooq Saeedi
Benefits and Issues:
Life and death are in the hands of Allah.
However, for the purpose of protection, carrying weapons and wearing armor, etc., is legislated.
And this is not contrary to tawakkul (reliance upon Allah).
Source: Sunan Abu Dawood – Commentary by Shaykh Umar Farooq Saeedi, Page: 2590