וַיְבַקֵּ֥שׁ דָּוִ֛ד אֶת־הָאֱלֹהִ֖ים בְּעַ֣ד הַנָּ֑עַר וַיָּ֤צָם דָּוִד֙ צ֔וֹם וּבָ֥א וְלָ֖ן וְשָׁכַ֥ב אָֽרְצָה׃
David therefore besought God for the child; and David fasted, and as often as he went in, he lay all night upon the earth.
Read halakhic rulings (Jewish law) on II Samuel 12:16: and classical halakhic sources.