בָּעֵ֣ת הַהִ֔יא בִּרְא֤וֹת דָּוִיד֙ כִּי־עָנָ֣הוּ יְהוָ֔ה בְּגֹ֖רֶן אָרְנָ֣ן הַיְבוּסִ֑י וַיִּזְבַּ֖ח שָֽׁם׃
At that time, when David saw that the LORD had answered him in the threshing-floor of Ornan the Jebusite, then he sacrificed there.
Read halakhic rulings (Jewish law) on I Chronicles 21:28: and classical halakhic sources.