Даниэль 8:2 Мидраш: Mekhilta DeRabbi Yishmael, Esther Rabbah & Midrash Tanchuma

And even though He spoke with them outside the land in the merit of the fathers, He did so only in a clean place, one of water. As it is written (Daniel 10:4) "And I was by the stream Ulai," (Ibid. 10:4) "and I was by the great river, the Tigris," (Ezekiel 1:3) "The word of the L–rd came to Ezekiel … by the river Kevar."

“That was in the Shushan citadel” – Rabbi Pinḥas said in the name of Rabbi Ḥananel: The Holy One blessed be He said to him: Cyrus referred to the name of His city and the name of His province,¹⁹The name of God’s city and God’s province.as he said: “In Jerusalem, which is in Judah” (Ezra 1:2); I, too, will refer to the name of your city and the name of your province, as it is stated: “That was in the Shushan citadel which is in the province of Elam” (Daniel 8:2).

Why did He speak to the prophets outside the land of Israel? Because of the merit of the patriarchs, as it is stated: A voice is heard in Ramah (Jer. 31:15). And after that it is written: Thus saith the Lord: “Refrain thy voice from weeping” (ibid., v. 16). Even outside the land (however), He spoke to the prophets only in places that were ritually clean, as in the case of Daniel: As I was by the side of the great river, which is Tigris (Dan. 10:4), and also: And I was by the stream Ulai (ibid. 8:3).⁶The rivers offered the opportunity to obtain ritual cleanliness. Ezekiel said to Him: As I was among the captives by the river Chebar (Ezek. 1:1). This was the Tigris. When did He speak to him? Outside the land only after he had previously spoken to him in the land, as it is said: Rise, go forth into the plain, and I will there speak with thee (ibid. 3:22).