This Halacha is an excerpt from our Sefer
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Early Minyan: On Erev Pesach, one is to wake up early to Daven Shacharis in Shul in order for one to finish his [Chametz] meal prior to the end of the 4th hour of the day.
 Admur 429:13; Kama 1:17; 51:1; Siddur Admur; Kitzur SHU”A 14:5
Other Opinions: Some are accustomed to recite Mizmor Lesoda on Erev Pesach. [See Tzemach Tzedek Chidushim Pesachim p. 208 who defends the custom; See Rebbe in Igros Kodesh 3 p. 71-72]
 The reason: This is due to that the Toda sacrifice contained a Chametz bread offerings and was thus not allowed to be brought on Erev Pesach being that it diminishes its eating time. [Kama 1:17; 51:1] It cannot be brought on Erev Pesach even before midday as this would then diminish in its amount of time that it would be allowed to be eaten. [M”B 429:12]