erō

This is the ordinary New Testament verb for saying, met in the forms that mean "I will say" and "I have said." Greek's everyday word for saying, λέγω, does not build those forms for itself, so it borrows them here, and the two work as one verb spread across different forms: λέγω for "says," εἶπον for "said," and this word for "will say," "has said," and "it was said." Nothing in the meaning changes at the handover.

Because it supplies those forms, this word ends up carrying several of the New Testament's most memorable set phrases. Matthew's refrain about Scripture coming true, "what was spoken by the prophet," runs through his whole Gospel. Each of the six sharp contrasts in the Sermon on the Mount opens "you have heard that it was said." Paul's argument in Romans keeps turning on the question "what shall we say then?" And Hebrews quotes God with "he has said."

Each of those phrases is doing a particular job:

• "It was said" names a word already on the books, which lets Jesus quote a command in the Sermon on the Mount without naming who gave it.
• "What shall we say then?" is not a request for information but a way of raising the objection an argument has to answer.
• "But someone will say" puts words in an imagined critic's mouth so that the writer can answer them.
• "He has said," used of God, presents a word spoken once and never taken back, which is why Hebrews reaches for it when quoting Scripture.

The plain uses far outnumber the formulas. Most often the word simply reports what a person will say or has said: the younger son rehearsing his confession on the road home in Luke 15:18, or Paul's blunt "I will speak the truth" in 2 Corinthians 12:6.