Halakhah su Salmi 69:13

At Minchah before reading the Torah we say: Va'ani sefilasi "But as for me, may my prayer etc." This is in accordance with the interpretation of our Sages of blessed memory³⁵Midrash cited in Tur 292. of the verse: "They talk of me, those who sit in the gate, and (about me) are the songs of drunkards." And immediately thereafter it is written: "But as for me, may my prayer …" etc.³⁶Psalms (69: 13). King David said before the Holy One Blessed is He, "Master of the Universe, this Nation is not like other nations of the world. Other nations of the world when they drink, they get drunk, and become boisterous, but we are not like that, for even though we drink, we say 'But as for me, may my prayer …' etc." Therefore this verse is recited before the reading of the Torah to give thanks to our Creator that He has not assigned our portion like theirs for even the ignorant among us come to hear the reading of the Torah. On Yom Tov which occurs on a weekday, since the Torah is not read, Va'ani sefilasi is not said.³⁷Rashi in Sefer Hapardess and Shibolei Haleket are the source of this ruling (126), Ezra did not ordain that the Torah be read at Minchah on Yom Tov. Rashba (Vol. 5, responsum 1) rules that this pasuk is said only on Shabbos because Shabbos is a time of great favor for Israel, more so than on Yom Tov. This reason is also mentioned in the Zohar (Vol. 2, 156). But on Shabbos even though there is no seifer Torah from which to read, nevertheless it is said.³⁸This ruling concurs with Eliyahu Rabba, Peri Megadim, Derech Hachaim, and Mishnah Berurah. Magein Avraham however rules that it is said only when there is a seifer Torah present. In such an event it is said before the Half Kaddish in order that there be no interruption between Kaddish and Shemoneh esreih.