The 4th Haftorah of Nechama, from the Book of Yesha'ayahu is רוני עקרה לא ילדה (Yesha'aya ch. 54 / ישעיהו פרק נד). The prophet Yesha'ayhu explains in a command to build up Jerusalem, a city that is barren - עקרה.
Yesha'ayhu's main message is for Israel to not let themselves be complacent, rather continue to build, grow and expand in Israel. The People of Israel are on the brink of destruction and being exiled. Jerusalem should be "Rina" - a source of joy!
Rav Listman discusses what other messages Yesha'ayahu delivers in his prophecy, and how the People of Israel should build up Jerusalem.