וַיָּ֧שֶׂם דָּוִ֛ד אֶת־הַדְּבָרִ֥ים הָאֵ֖לֶּה בִּלְבָב֑וֹ וַיִּרָ֣א מְאֹ֔ד מִפְּנֵ֖י אָכִ֥ישׁ מֶֽלֶךְ־גַּֽת׃
And David laid up these words in his heart, and was sore afraid of Achish the king of Gath.
Read kabbalistic (mystical) interpretation of I Samuel 21:13: and classical mystical sources.