isaiah 7:12 But Ahaz said, I will not ask, neither will I tempt the LORD. - Free Bible Online

      12. neither . . . tempt--hypocritical pretext of keeping the law (De 6:16); "tempt," that is, put God to the proof, as in Mt 4:7, by seeking His miraculous interposition without warrant. But here there was the warrant of the prophet of God; to have asked a sign, when thus offered, would not have been a tempting of God. Ahaz' true reason for declining was his resolve not to do God's will, but to negotiate with Assyria, and persevere in his idolatry (2Ki 16:7, 8, 3, 4, 10). Men often excuse their distrust in God, and trust in their own devices, by professed reverence for God. Ahaz may have fancied that though Jehovah was the God of Judea and could work a sign there, that was no proof that the local god of Syria might not be more powerful. Such was the common heathen notion (Isa 10:10, 11; 36:18-20).

JFB.