י"ד שחל להיות בשבת בודקין ליל י"ג ומבערים הכל לפני השבת ומשיירין מזון שני סעודות לצורך השבת דסעודה שלישית זמנה אחר המנחה ואז אינו יכול לעשותה לא במצה ולא בחמץ אלא במצה עשירה וצריך לעשותה קודם שעה עשירית: הגה ובמדינות אלו שאין נוהגין לאכול מצה עשירה כדלקמן סימן תס"ב סעיף ד' בהג"ה יקיים סעודה שלישית במיני פירות או בבשר ודגים כדלעיל סי' רצ"א סעיף ה' בהגה:

When the 14th of Nissan occurs on Shabbat we search for Hametz on the 13th and burn everything before Shabbat and we leave over enough food for the first two Shabbat meals for the timing of the third meal is after Mincha time and at that time we are not able to have the meal with either matzah or hametz rather with matzah ashirah (egg matzah) and the meal should be eaten before the tenth hour. Rema: And in our lands where we don't eat matzah ashirah (egg matzah) as said above in section 462:4 we have the third meal with fruit or meat or fish as is found above in 291:5.

It is good to burn [the leaven] on the eve of Sabbath before noon, in order to avoid making the mistake in other years of burning after noon (and on the Sabbath day he should nullify it) (Tur).

We do not cook porridge or anything like it for this Sabbath, and we do not make shrunken bread in a bowl. Rem"a: And if one transgressed and cooked [something like it] and the food is stuck to the pan, and it is impossible to clean, one should rub it a little to remove the leaven.

After one has eaten the morning meal this Sabbath, he should shake out the table cloth that they ate with, and clean the plates with his finger, and hide them with his other utensils of leaven. And if bread remains, one may give it to a stranger on the condition that he not go out to the public domain with it, [even if that condition is given] dishonestly, and [only bread of] a small amount.

If leaven remains after they ate, he should nullify it and cover it with a vessel, until after the Festival, and burn it.

Even if no leaven remains in the house after the morning meal - he must nullify leaven the way he nullifies it in other years."

One who is traveling on the fourteenth [of Nisan] for the sake of a mitzvah, such as to circumcise his son or to partake in a betrothal meal at his father-in-law’s house, and remembers that he has leaven in his home: if he is able to return to his house, remove it, and then go back to his mitzvah, he should return and remove it; but if not, he should nullify it in his heart. If he was going to rescue [someone] from a river, from a fire, from a collapse, or from [danger posed by] non-Jews, he should nullify it in his heart and not return, even if there is time. If he left for his own personal needs, he must return immediately. Up to what point must he return? Up to the amount of an egg; for less than this, he nullifies it in his heart and that suffices.

If he had dough in his house and he is occupied elsewhere, and he fears that it may become leaven, he should nullify it in his heart before it becomes leaven; but if it already became leaven, nullification is not effective if this is after the time when it is prohibited.