Charles Spurgeon Commentary Hebrews 3:12-13

"Take heed, brethren, lest haply there shall be in any one of you an evil heart of unbelief, in falling away from the living God: but exhort one another day by day, so long as it is called To-day; lest any one of you be hardened by the deceitfulness of sin:" — Hebrews 3:12-13 (ASV)

Take heed, brethren, lest there be in any of you an evil heart of unbelief, in departing from the living God. But exhort one another daily, while it is called Today; lest any of you be hardened through the deceitfulness of sin.

Watch over each other as well as over yourselves. Take heed that sin does not harden you before you are aware of it; even while you imagine that you have wiped it out by repentance, petrifaction will remain on your heart through the deceitfulness of sin.