וַיְהִ֕י מִקֵּ֖ץ אַרְבָּעִ֣ים שָׁנָ֑ה וַיֹּ֤אמֶר אַבְשָׁלוֹם֙ אֶל־הַמֶּ֔לֶךְ אֵ֣לֲכָה נָּ֗א וַאֲשַׁלֵּ֛ם אֶת־נִדְרִ֛י אֲשֶׁר־נָדַ֥רְתִּי לַֽיהוָ֖ה בְּחֶבְרֽוֹן׃
And it came to pass at the end of forty years, that Absalom said unto the king: ‘I pray thee, let me go and pay my vow, which I have vowed unto the LORD, in Hebron.
Numbers
If a man makes a vow to Adonoy or makes an oath; to initiate a prohibition himself; he may not profane his word. He shall do all that he said.