Charles Ellicott Commentary Psalms 95:8

"Harden not your heart, as at Meribah, As in the day of Massah in the wilderness;" — Psalms 95:8 (ASV)

The mention of the guiding voice suggests to the poet to make God Himself address His people, and with this verse the Divine warning begins.

Provocation ... temptation. —It is better to keep here the proper names Meribah and Massah (Exodus 17:1–7; Numbers 20:13).