וַיַּחְגֹּ֣ר דָּוִ֣ד אֶת־חַ֠רְבּוֹ מֵעַ֨ל לְמַדָּ֜יו וַיֹּ֣אֶל לָלֶכֶת֮ כִּ֣י לֹֽא־נִסָּה֒ וַיֹּ֨אמֶר דָּוִ֜ד אֶל־שָׁא֗וּל לֹ֥א אוּכַ֛ל לָלֶ֥כֶת בָּאֵ֖לֶּה כִּ֣י לֹ֣א נִסִּ֑יתִי וַיְסִרֵ֥ם דָּוִ֖ד מֵעָלָֽיו׃
And David girded his sword upon his apparel, and he essayed to go, [but could not]; for he had not tried it. And David said unto Saul: ‘I cannot go with these; for I have not tried them.’ And David put them off him.
Find Mishnaic references to I Samuel 17:39: passages from the 63 tractates of the Mishnah that cite or discuss this verse, free.