What does Daniel 10:4 mean?

Daniel was standing near the Tigris River on the twenty-fourth day of the first month. There, he experienced an addition to his final recorded vision (Daniel 10:1). The month he specifies in this verse was April or the month of Abib, later called Nissan (Nehemiah 2:1). Exodus 23:15 places the Feast of Unleavened Bread in Abib. Likely, Daniel had kept the Passover on the fourteenth day of Abib and the Feast of Unleavened Bread that began the next day and continued to the twenty-first day.

The Tigris and the Euphrates were separated by about thirty-five miles—or fifty-six kilometers—and not far from Babylon. Daniel may have been traveling on government business when he reached the Tigris River. He was not dreaming or just seeing the Tigris in a vision, as some expositors suppose. He was physically present at the site.

Daniel was either already in mourning when he saw a vision or what he saw in his vision caused him to mourn (Daniel 10:1–3). Here, he begins to learn more about the future from an impressive source (Daniel 5:5–6).