Hebrews 3:8

“Harden not you hearts, etc..] There is a natural hardness of the heart; the heart of man is like a stone, destitute of spiritual life, motion, and activity; it is senseless, stupid, impenitent, stubborn, and inflexible, on which no impressions can be made, but by powerful grace: and there is an acquired, habitual, and voluntary hardness of heart, to which men arrive by various steps; as entertaining pleasing thoughts of sin; an actual commission of it, with frequency, till it becomes customary, and so habitual; an extenuation or justification of it, and so they become hardened against all reproofs and sermons, and to all afflictions and judgments; are insensible and past feeling, and openly…”

“Harden not your hearts--This phrase here only is used of man's own act; usually of God's act (Rom 9:18). When man is spoken of as the agent in hardening, the phrase usually is, "harden his neck," or "back" (Neh 9:17). provocation . . . temptation--"Massah-meribah," translated in Margin "tentation . . . chiding," or "strife" (Exo 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. Num 20:1-13 and Deu 33:8 mention a second similar occasion in the wilderness of Sin, near Kadesh, also called…”

“Harden not your hearts - Do not render the heart insensible to the divine voice and admonition. A hard heart is that where the conscience is seared and insensible; where truth makes no impression; where no religious effect is produced by afflictions; where preaching is listened to without interest; and where the mind is unaffected by the appeals of friends. The idea here is, that a refusal to listen to the voice of God is connected with a hardening of the heart. It is in two ways: The very refusal to do this tends to harden it. And, (2)In order to resist the appeals of God, people must resort to the means of “voluntarily” hardening the heart. This they do by setting themselves against the…”

“As in the provocation - When Israel provoked me by their strife and murmurings. In the day of temptation - When at the same time they tempted me, by distrusting my power and goodness. Exo 17:7. Hebrews 3:9”

“3:8 Israel . . . rebelled and tested God in places such as Massah and Meribah, where there was a shortage of water (Exod 17:1-7; Num 20:2-13), and especially at Kadesh, where the disobedient Israelites refused to enter the Promised Land (Heb 3:10; see Num 14:1-25; Deut 1:19-46; Ps 106).”

“Harden: Heb 3:12, Heb 3:13; Exo 8:15; Sa1 6:6; Kg2 17:14; Ch2 30:8, Ch2 36:13; Neh 9:16; Job 9:4; Pro 28:14, Pro 29:1; Jer 7:26; Eze 3:7-9; Dan 5:20; Zac 7:11, Zac 7:12; Mat 13:15; Act 19:9; Rom 2:5, Rom 2:6 as: Num 14:11, Num 14:22, Num 14:23; Deu 9:22-24; Psa 78:56 of: Exo 17:7; Deu 6:16; Psa 78:18, Psa 106:14; Co1 10:9 Hebrews 3:9”