8. Harden not your hearts--This phrase here only is used of man's own act; usually of God's act (Ro 9:18). When man is spoken of as the agent in hardening, the phrase usually is, "harden his neck," or "back" (Ne 9:17).
      provocation . . . temptation--"Massah-meribah," translated in Margin "tentation . . . chiding," or "strife" (Ex 17:1-7). Both names seem to refer to that one event, the murmuring of the people against the Lord at Rephidim for want of water. The first offense especially ought to be guarded against, and is the most severely reproved, as it is apt to produce many more. Nu 20:1-13 and De 33:8 mention a second similar occasion in the wilderness of Sin, near Kadesh, also called Meribah.
      in the day--Greek, "according to the day of."

JFB.