- Question: [Thursday, 25th Shevat 5782]
On Shabbos, towards the end of the blessing of Yishtabach, I realized that I forgot to say Nishmas [I went straight to Yishtabach after finishing Az Yashir]. May I make it up now and read between Yishtabach and the blessing of Yotzer Or?
Yes, you are to say Nishmas in between Yishtabach and Yotzer Or. However, if you already began Yotzer Or, then it cannot be made up.
Explanation: It is permitted for one to make up between Yishtabach and Yotzer Or any skipped prayers that were supposed to be said during Pesukei Dezimra. The reason for this is because the prohibition against making an interval between Yishtabach and Yotzer Or is only regarding mundane matters, however, to mention praise of Hashem which is similar to its content is certainly allowed.
Sources: See Birkeiy Yosef 281 in name of Michtam Ledavid 13 “One who forgot to say Nishmas and already said Yishtabach as he is accustomed during the week, is to say Nishmas after Yishtabach,” brought in Shaareiy Teshuvah 281:1; Ben Ish Chaiy Toldos 2; Kaf Hachaim 281:7; Ateres Zekeinim 56 regarding certain Pesukim that “One may say these verses even between Yishtabach and Yotzer and need not worry of a Hefsek.”; Meorer Yisheinim 183; Piskeiy Teshuvos 54:3; See Admur 54:4 and other Poskim [Rama 54:2; M”A 54:3; Kol Bo 6; Sefer Hamachkim; Orchos Chaim] who all rule that if the Chazan made a Hefsek after Yishtabach he is to repeat some of the Pesukei Dezimra; See Admur 51:4; 53:3; 54:3 and other Poskim [Michaber and Rama 54:1; Tur in name of Seder Rav Amram Gaon; Kol Bo 4] who rule one may make an interval between Yishtabach and Yotzer Or for the sake of a Mitzvah; See Shevet Hakehasi 6:65; Kovetz Teshuvos 1:19