Call unto me, and I will answer thee, and shew thee great and mighty things, which thou knowest not.

King James Translators' Notes

mighty: or, hidden

Jamieson-Fausset-Brown Bible Commentary

3. Call . I will answer-(Jer 29:12; Ps 91:15). Jeremiah, as the representative of the people of God, is urged by God to pray for that which God has determined to grant; namely, the restoration. God's promises are not to slacken, but to quicken the prayers of His people (Ps 132:13, 17; Isa 62:6, 7).

mighty things-Hebrew, "inaccessible things," that is, incredible, hard to man's understanding [Maurer], namely, the restoration of the Jews, an event despaired of. "Hidden," or "recondite" [Piscator].

thou knowest not-Yet God had revealed those things to Jeremiah, but the unbelief of the people in rejecting the grace of God had caused him to forget God's promise, as though the case of the people admitted of no remedy.

Matthew Henry's Concise Commentary

33:1-13 Those who expect to receive comforts from God, must call upon him. Promises are given, not to do away, but to quicken and encourage prayer. These promises lead us to the gospel of Christ; and in that God has revealed truth to direct us, and peace to make us easy. All who by sanctifying grace are cleansed from the filth of sin, by pardoning mercy are freed from the guilt. When sinners are thus justified, washed, and sanctified in the name of the Lord Jesus, and by the Holy Spirit, they are enabled to walk before God in peace and purity. Many are led to perceive the real difference between the people of God and the world around them, and to fear the Divine wrath. It is promised that the people who were long in sorrow, shall again be filled with joy. Where the Lord gives righteousness and peace, he will give all needful supplies for temporal wants; and all we have will be comforts, as sanctified by the word and by prayer.