בַּת־בָּבֶ֗ל הַשְּׁד֫וּדָ֥ה אַשְׁרֵ֥י שֶׁיְשַׁלֶּם־לָ֑ךְ אֶת־גְּ֝מוּלֵ֗ךְ שֶׁגָּמַ֥לְתְּ לָֽנוּ׃
O daughter of Babylon, that art to be destroyed; Happy shall he be, that repayeth thee As thou hast served us.
Read halakhic rulings (Jewish law) on Psalms 137:8: and classical halakhic sources.