Q. Is it allowed to go and be menachem ovel (comforting) someone sitting shiva on Tisha Beav? Before or after noon? What are the words we should one say then?
A. Igrois Moishe (O.H. 5: 20: 22) writes that nichum avelim on Tisha Beav should not be done until after chatzos, since words of consolation should not be mentioned before that time. However, he adds that if one is leaving town, he may do so even on the night before, but should refrain from words of consolation. Nevertheless, he can say the customary blessing of “Hamakom Yenachem” even then.
See also similar in Nitei Gavriel p. 438, Chaye Moshe p. 246, and Halichos Emes p. 191.
Horav Shlomo Miller’s Shlit’a opinion is similar.
Rabbi A. Bartfeld as advised by Horav Shlomo Miller and Horav Aharon Miller Shlit’a