Reference for I Chronicles 21:19

וַיַּ֤עַל דָּוִיד֙ בִּדְבַר־גָּ֔ד אֲשֶׁ֥ר דִּבֶּ֖ר בְּשֵׁ֥ם יְהוָֽה׃

And David went up at the saying of Gad, which he spoke in the name of the LORD.

BDB