Acts 26:7

Unto which promise - To the fulfillment of which promise they hope to come; that is, they hope and believe that the promise will be fulfilled, and that they will partake of its benefits.

Our twelve tribes - This was the name by which the Jews were designated. The ancient Jewish nation had hoped to come to that promise; it had been the hope and expectation of the nation. Long before the coming of the Messiah, ten of the twelve tribes had been carried captive to Assyria, and had not returned, leaving but the two tribes of Benjamin and Judah. But the name, “the twelve tribes,” as used to designate the Jewish people, would be still retained. Compare James 1:1. Paul here says that the hope referred to had been that of the Jewish nation. Except the comparatively small portion of the nation, the Sadducees, the great mass of the nation had held to the doctrine of a future state. This Agrippa would know well.

Instantly - Constantly; with intensity ἐν en ἐκτένεια ekteneia; with zeal. This was true, for, amidst all the sins of the nation, they observed with punctuality and zeal the outward forms of the worship of God.

Serving God - In the ordinances and observances of the temple. As a nation they did not serve him in their hearts, but they kept up the outward forms of religious worship.

Day and night - With unwearied zeal; with constancy and ardor, Luke 2:37. The ordinary Jewish services and sacrifices were in the morning and evening, and might be said to be performed day and night. Some of their services, as the Paschal supper, were prolonged usually until late at night. The main idea is, that they kept up the worship of God with constant and untiring zeal and devotion.

For which hope’s sake - On account of my cherishing this hope in common with the great mass of my countrymen. See Acts 23:6. If Paul could convince Agrippa that the main point of his offence was what had been the common belief of his countrymen, it would show to his satisfaction that he was innocent. And on this ground he put his defense - that he held only what the mass of the nation had believed, and that he maintained this in the only consistent and defensible manner that God had, in fact, raised up the Messiah, and had thus given assurance that the dead would rise.