I Chronicles 21:7 Kabbalah

וַיֵּ֙רַע֙ בְּעֵינֵ֣י הָאֱלֹהִ֔ים עַל־הַדָּבָ֖ר הַזֶּ֑ה וַיַּ֖ךְ אֶת־יִשְׂרָאֵֽל׃ (פ)

And God was displeased with this thing; therefore He smote Israel.

Read kabbalistic (mystical) interpretation of I Chronicles 21:7: and classical mystical sources.