Shulchan Arukh, Orach Chayim Siman 458
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.
מצוה ללוש המצה בערב פסח. ובו סעיף אחד
נוהגים שלא ללוש מצת מצוה בערב פסח עד אחר שש שעות שהוא זמן הקרבת קרבן פסח ובי"ד שחל להיות בשבת לשין בערב שבת אחר שש שעות:
Mishna Berura Yomi
THE COMMANDMENT TO KNEAD THE MATZAH OF THE EVE OF PESACH: ONE SECTION It is customary to not knead Matzot Mitzvah on the eve of Pesach until after the sixth hour, as this was the time when the Pesach offering was offered. When the 14th [of Nissan] falls out on Shabbos, one should knead on the eve of Shabbos after the sixth hour.