Daniel 10:2

“In those days I Daniel was mourning, etc.] Either on account of what had been revealed to him in the last vision or prophecy of the seventy weeks; by which it appeared what wickedness the people of the Jews would be guilty of in cutting off the Messiah; and what desolations would come upon their land, city, and temple, for such usage of him: as also because of the present case of his people; many of them continuing in the country of Babylon, when they had liberty to return to their land: or because of the hinderance the Jews met with in rebuilding their city and temple, who had returned thither; of which Daniel had an account, and which caused him to mourn in secret: and so he continued…”

“mourning--that is afflicting myself by fasting from "pleasant bread, flesh and wine" (Dan 10:3), as a sign of sorrow, not for its own sake. Compare Mat 9:14, "fast," answering to "mourn" (Dan 10:15). Compare Co1 8:8; Ti1 4:3, which prove that "fasting" is not an indispensable Christian obligation; but merely an outward expression of sorrow, and separation from ordinary worldly enjoyments, in order to give one's self to prayer (Act 13:2). Daniel's mourning was probably for his countrymen, who met with many obstructions to their building of the temple, from their adversaries in the Persian court.”

“In those days I Daniel was mourning - I was afflicting myself; that is, he had set apart this time as an extraordinary fast. He was sad and troubled. He does not say on what account he was thus troubled, but there can be little doubt that it was on account of his people. This was two years after the order had been given by Cyrus for the restoration of the Hebrew people to their country, but it is not improbable that they met with many embarrassments in their efforts to return, and possibly there may have sprung up in Babylon some difficulties on the subject that greatly affected the mind of Daniel. The difficulties attending such an enterprise as that of restoring a captured people to their…”

“Was mourning - Because he foresaw the many calamities that would befall the Jews for their sins, especially for destroying the Messiah, and rejecting his gospel. Daniel 10:4”

“10:2-3 Daniel was apparently in mourning because of his previous visions (10:14, 16).”

“I Daniel: Ezr 9:4, Ezr 9:5; Neh 1:4; Psa 42:9, Psa 43:2, Psa 137:1-5; Isa 66:10; Jer 9:1; Mat 9:15; Rom 9:2; Jam 4:9; Rev 11:5 full weeks: Heb. weeks of days, Dan 9:24-27 Daniel 10:3”

“Dan 10:2, Dan 10:3 introduce the following revelation by a statement of the occasion of it. ההם בּימים refers back to the date named in Dan 10:1. The ימים after שׁבעים does not serve to designate the three weeks as common day-weeks, in contrast to the שׁבעים of Dan 9:24., but is an accusative subordinated to the definition of time which expresses the idea of continuance: three weeks long, or three whole weeks, as Gen 41:1; cf. Gesen. Gramm. 118, 3. For three weeks Daniel mourned and fasted, i.e., abstained from the usual food. חמות לחם, precious food, delicacies; but Hv., v. Leng., Maur., Hitz., and Kran. interpret it of leavened bread, so called in contrast to the unleavened paschal bread,…”