testificar
/testifiˈkaɾ/ · B1 · verb
to testify
⚖️ testificar = testi (witness) + ficar (to make): to make yourself a witness
From Latin testificari: testis (witness) + facere (to make, do). English testify comes from the same root. Spanish testigo means witness, so testificar is what a testigo does in court.