David
Psalm 116:10ESV·traditional attribution

I believed, even when I spoke: “I am greatly afflicted”;

John Calvin Reformed @genevareformer

PSALM 116 David, being delivered out of very great dangers, relates what cruel torment and anguish of mind he endured, and then how remarkably he was preserved by God. The desperate state of matters with him tended to make the power of God in his preservation more conspicuous; for had not God interposed for his deliverance, all hope would have failed.

Commenting on Psalm 116:1-19

C.H. Spurgeon Reformed Baptist @princeofpreachers

I believed, therefore have I spoken. I could not have spoken thus if it had not been for my faith: I should never have spoken unto God in prayer, nor have been able now to speak to my fellow men in testimony if it had not been that faith kept me alive, and brought me a deliverance, whereof I have good reason to boast.

Matthew Henry Presbyterian @wholebiblehenry

The Septuagint and some other ancient versions make these verses a distinct psalm separate from the former; and some have called it the Martyr's psalm, I suppose for the sake of Psa 116:15. Three things David here makes confession of: - I. His faith (Psa 116:10): I believed, therefore have I spoken.

Commenting on Psalm 116:10-19