“[…] You should know for a certainty that I have warned you today that your error will cost you your lives.”
~Jeremiah 42:19,20

After the Chaldeans took most of the Jews captive, the army chiefs along with the remaining people in the vicinity of Jerusalem asked the prophet to pray on their behalf and find out what God’s will for them was. (Jer. 42:1-3)
Ten days later, Jehovah gave his reply, asking them to remain there and not fear the king of Babylon. (Jer. 42:7,10,11)
But the people had allowed their fear to overcome them and were headstrong about fleeing to Egypt (Jer. 43:4-7)
Eventually, the Chaldeans extended their battles into Egypt, and that remnant did not survive (Jer. 43:10,11)
They were not necessarily evil people.
They mostly consisted of the poorest sector of the population. (Jer. 40:7)
The fact that they first sought out God’s guidance indicates that at least at one point they had the right intention. (Jer. 42:5,6)
But their subsequent decision to ignore Jehovah’s commandment and head on into Egypt without his blessing ended up having tragic consequences.
Today, God warns us that a time is coming in which he will judge all of humanity. (Mark 13:32,33; Acts 17:30,31)
If we were in the habit of praying for his guidance and then ignoring Biblical counsel, we, too, would be falling in an error that will cost us our lives.