It sounds like you might be thinking of
Hebrews 12:17. It says:
"For you know that afterward, when he desired to inherit the blessing, he was rejected, for he found no place for repentance, though he sought it with tears."
This verse refers to Esau, who sold his birthright to his brother Jacob for a single meal. Later, when he wanted the blessing associated with the birthright back, he was unable to obtain it, despite desperately seeking a way to reverse his decision.
It's important to note that the verse doesn't say Esau sought *God's* repentance but the repentance of his father.