16 Then Cain went out from the presence of the LORD, and settled in the land of Nod, east of Eden.
17 Cain had relations with his wife and she conceived, and gave birth to Enoch; and he built a city, and called the name of the city Enoch, after the name of his son. 18 Now to Enoch was born Irad, and Irad became the father of Mehujael, and Mehujael became the father of Methushael, and Methushael became the father of Lamech. 19Lamech took to himself two wives: the name of the one was Adah, and the name of the other, Zillah. 20 Adah gave birth to Jabal; he was the father of those who dwell in tents and have livestock. 21 His brother’s name was Jubal; he was the father of all those who play the lyre and pipe. 22 As for Zillah, she also gave birth to Tubal-cain, the forger of all implements of bronze and iron; and the sister of Tubal-cain was Naamah.
23 Lamech said to his wives,
“Adah and Zillah,
Listen to my voice,
You wives of Lamech,
Give heed to my speech,
For I have killed a man for wounding me;
And a boy for striking me;
24 If Cain is avenged sevenfold,
Then Lamech seventy-sevenfold.”
25 Adam had relations with his wife again; and she gave birth to a son, and named him Seth, for, she said, “God has appointed me another offspring in place of Abel, for Cain killed him.” 26 To Seth, to him also a son was born; and he called his name Enosh. Then men began to call upon the name of the LORD.
We don’t really have much idea of the time frame here, but we are given a listing of several generations of Cain’s descendants, and then we find out about the firstborn of Seth, Adam and Eve’s third son. Regardless, it seems that the children of Cain did not ‘call upon the name of the LORD.’ It was not until Enosh was born that men returned to God. Cain, and presumably even Adam and Eve, had some issues here. Even though they had lost the intimate fellowship with God, they could still pray to him, and Abel had apparently done so, hence his sacrifice to God. But no one had until Enosh was born, likely a hundred years or more after Abel died. We (through Jesus) have the ability to come into God’s presence even closer than they did. Don’t wait for something great (or horrible) to happen before you pray. As it says in Thessalonians, we should always be praying. We should always be communicating with our God. Press in, and see what God will do.