Bearing in mind that Nachshon brought his Korban on Sunday (See Pasuk 13), how could Elishama ben Amihud bring a Korban Yachid on Shabbos?
Da'as Zekeinim: Because Yosef kept Shabbos before the Torah was given, as the Torah indicates in Vayeishev, Bereishis 43:16 "u'Tevo'ach Tevach Vehachein. 1 "
Moshav Zekeinim: Since Vehachein" hints at Shabbos - as in Beshalach, Sh'mos, 16:5 "ve'Hayah ba'Yom ha'Shishi Veheichinu ... ". Also the Pasuk in Tehilim 60:9 "Li Gil'ad... ve'Efrayim Ma'oz Roshi ..." alludes to [Hora'os Sha'ah - a. to the Korban of] Eliyahu on Har ha'Karmel, of Gidon, and b. to the Korban of the Nasi of Efrayim on Shabbos; Also Yehoshua who was from Efrayim conquered Yericho on Shabbos, and David sinned to open the door for Ba'alei Teshuvah - Hashem made the temptation too great to coerce him into sinning (PF).
