Strong's G4303 — προμαρτύρομαι (verb)
promarturomai (prom-ar-too'-rom-ai) v.
1. to be a witness in advance i.e. predict
[from G4253 and G3143]
KJV: testify beforehand 
Root(s): G4253, G3143 
Hebrew root: μαρτύρομαι
Occurrences: 1