Zayd Bin Harithah (R.A) or in the Arabic accent it is pronounced as Zaid Bin Haris (R.A). He (R.A) was one of the early companions of the Holy Prophet (P.B.U.H) and also He was the adopted son of the Holy Prophet Hazrat Muhammad (P.B.U.H). According to the resources, He was the third person who accepted Islam after Hazrat Ali (R.A) and Hazrat Khadija (R.A).

Zayd (R.A) used to be a slave to the Holy wife Hazrat Khadija (R.A), before her death She (R.A) gave him to the Holy Prophet (P.BU.H). He later freed Zayd (R.A) and gave him the title of his adopted son. Zayd (R.A) was a skilled commander and led many battles for the Muslims in the life of the Holy Prophet (P.B.U.H). Zayd (R.A) was killed at the battle of Mutah in 629 C.E

https://en.wikipedia.org/wiki/Zayd_ibn_Harithah