Maaseh Rav Siman 28
Can copy this into an AI, or connect the whole library to your assistant. For deeper learning, you can directly use the original seforim, sites, and apps.
בפסד"ז אתה ה' לא תכלא רחמיך ממני ביו"ד והאומר בוא"ו שבוש הוא בידו. באשרי זכר רב טובך ב' סגלין:
Sefaria Community Translation
In 'Pesukei Dezimra' the phrase "You, GD, don't withhold Your mercy from me" is with a Yud, and one who says it with a Vav is in error [Lit: on his hand]. In the paragraph of 'Ashrei' the phrase "They will recount your bountiful goodness" contains two Segol (vowels). (Presumably on the word 'Zecher')