With a strong hand and an outstretched arm
With a strong hand and an outstretched arm (בְּיָ֣ד חֲ֭זָקָה וּבִזְר֣וֹעַ נְטוּיָ֑ה כִּ֖י לְעוֹלָ֣ם חַסְדּֽוֹ)  is a phrase in Judaic tradition representing God's use of his power on behalf of the Jews.
In Exodus 6 (Parshat Va'eira in the Torah), Moses has just reiterated to God the complaint of the Israelites that every time he has gone to Pharaoh on their behalf, things have gotten worse for them; in this case, Pharaoh has now ruled that they shall henceforward make bricks without straw. God now replies to Moses that the time will come when Pharaoh himself will actually drive the Israelites out of Egypt; and that on behalf of his covenant with the Patriarchs, God will redeem the Israelites with a strong hand and an outstretched arm, so that they will know him.
Moses and Aaron did not reply directly to the Israelites regarding their complaint, but when Moses conveys this reply from God to the Israelites, it fails to lift their spirits.
The implication is that God will provide a lesson to both the Israelites and the nations of the world, showing his power and the futility of trying to resist it, as well as his willingness to use his power on behalf of his Covenant. To achieve this, the Pharaoh must have been seen not to be freeing the Israelites as an act of benevolence; but instead to be adamantly resistant at first, then changing his mind to the point where he actually drives them to leave, due only to his eventual reluctant submission to God's might.
This concept is repeated in the recount of the Plague of Hail. This serves as the introduction to the actual demonstrations of God's power, beginning with Aaron's Rod and followed by the Ten Plagues of Egypt.
The phrase has come to have great value in Judaic tradition as the symbol of God's use of his power on behalf of the Jews. It is repeated verbatim in Deuteronomy 26:8, which describes the commandment to tithe first fruits and which is read with emphasis in the Passover Haggadah and Seder.
- Psalm 136:12