וְהַיָּמִ֗ים אֲשֶׁר֩ מָלַ֨ךְ שְׁלֹמֹ֤ה בִירוּשָׁלִַ֙ם֙ עַל־כָּל־יִשְׂרָאֵ֔ל אַרְבָּעִ֖ים שָׁנָֽה׃
And the time that Solomon reigned in Jerusalem over all Israel was forty years.
Read halakhic rulings (Jewish law) on I Kings 11:42 from the Mishneh Torah and classical halakhic sources, free online.