Matthew 5:2 says that Jesus “opened his mouth and taught them, saying” (καὶ ἀνοίξας τὸ στόμα αὐτοῦ ἐδίδασκεν αὐτοὺς λέγων). If you were in a sarcastic mood you might respond, “How else would he teach? With a closed mouth?” This is why the NIV skips it entirely: “he began to teach them,” as well as most other translations (HCSB, NRSV, NET, NLT). They see it as unnecessarily redundant. The ESV, NASB, and KJV keep the phrase.
I did a search for the phrase “open* his/its mouth” (* allows the search to find “opens” and “opened”). There are seven in the Greek Testament (ESV). There are non-metaphorical uses such as Peter opening the mouth of the fish to find the coin (Matt 17:27), and the metaphor of the earth opening its mouth to swallow the water from the beast (Rev 12:16).
There are two verses of special interest. The beast opened its mouth to utter blasphemies (Rev 13:6). The point is not that the orifice below the nose opened, but that it said something.
In Acts 18:14 we read, “But when Paul was about to open his mouth, Gallio said to the Jews ….” The point is that Paul was stopped before he said something. And then there is Job; “Job opens his mouth in empty talk; he multiplies words without knowledge” (35:16). Also Prov 24:7; “wisdom is too high for a fool; in the gate he does not open his mouth.” The point in both is that Paul and the fool do even begin to say something.
This brings us to the important verses. “Then Philip opened his mouth, and beginning from this Scripture he announced the good news to him, Jesus” (Acts 8:35). “So Peter opened his mouth and said: “Truly I understand that God is not one who shows partiality” (Acts 10:34). What was implicit in the preceding paragraph is explicit here: “opening the mouth” sounds like a rhetorical device to add solemnity to what is going to be said.
When you check the Old Testament, you see similar verses. “Job opened his mouth and cursed the day of his birth” (Job 3:1; cf. 33:2). “And behold, one in the likeness of the children of man touched my lips. Then I opened my mouth and spoke” (Dan 10:16). Again, it feels like the phrase “opened his mouth” is a rhetorical device to add solemnity to the saying.
So does the phrase “to open one’s mouth” have any meaning, or is it so redundant that it should be skipped in translation? I think that there is enough of a pattern to show that it was a way of adding solemnity to what was to be said. Carson comments that it reflects OT roots and “is used in solemn or revelatory contexts.”
It is not that Jesus just started saying the Sermon on the Mount. He looked around at the audience and solemnly began his most memorable sermon.
We should be very careful at dropping out entire phrases in translation, even if there is not an easy counterpart in English.
William D. [Bill] Mounce posts about the Greek language, exegesis, and related topics at Koinonia. He is the author of numerous works including the recent Basics of Biblical Greek Video Lectures and the bestselling Basics of Biblical Greek. He is the general editor of Mounce's Complete Expository Dictionary of the Old and New Testament Words. He served as the New Testament chair of the English Standard Version Bible translation, and is currently on the Committee for Bible Translation for the NIV.