In the tenth chapter of Daniel, we read that Daniel lacked understanding of what would happen to Israel in the last days (Dan. 10:14), and so he began fasting. In his fast he did not eat any tasty food, eat meat, drink wine, or use any ointment; but he mourned in prayer for three weeks.
In those days I, Daniel, was mourning three full weeks.
Then finally, at the end of three weeks, an angel came to him with the answer to his prayer. But first he explained his delay: “Your prayers were heard on the very first day, and I immediately left to give you the answer. But an evil angel, the prince of the kingdom of Persia interrupted me and fought with me for three weeks. Then finally, at the end of the three weeks, the angel Michael came to help me” (v. 12, my own paraphrase).
So, as it happened, after three weeks of prayer and fasting, God gave Daniel an understanding of what would happen to Israel in the last days (v. 14). But I don’t think he would have received that understanding had he not so earnestly desired it and sought it out in prayer.
You too can receiver more understanding through prayer if you really desire it. The Bible tells us clearly that if we pray for wisdom and understanding God will give it to us (Prov. 2:6, Ja. 1:5). But we must keep praying and wait patiently for it; for the devil doesn’t want us to have God’s understanding; and he may send his demons to delay your prayers just as he did with Daniel.