Among the following, in whose custody was the seal of Holy Prophet (S.A.W)?

a) Hazrat Umar (R.A)

b) Hazrat Usman (R.A)

c) Hazrat Sharjil (R.A)

d) Hazrat Huzaifa (R.A) 

The seal that was affixed on the letters and other documents of Prophet Muhammad (PBUH) was in the custody of Hazrat Huzaifa (R.A). Hazrat Huzaifa bin Yaman (R.A) was among those who accepted Islam first.