Strong’s Greek
G5350 — phtheggomai
The entry below is Strong’s own definition (1890, public domain), and every verse where the word occurs.
φθέγγομαι
phtheggomai — pronounced ftheng'-gom-ahee
probably akin to 5338 and thus to 5346; to utter a clear sound, i.e. (generally) to proclaim:--speak. see GREEK for 5346 see GREEK for 5338
3 occurrences in the KJV.
Acts 4:18
And they called them, and commanded them not to speak at all nor teach in the name of Jesus.
2 Peter 2:16
But was rebuked for his iniquity: the dumb ass speaking with man’s voice forbad the madness of the prophet.
2 Peter 2:18
For when they speak great swelling words of vanity, they allure through the lusts of the flesh, through much wantonness, those that were clean escaped from them who live in error.