What is "that day"?
Radak: The day of the matter that will make everyone's ears ring, will begin the punishment against Beis Eli what Ish ha'Elokim said.
Why does it say "El Beiso"?
Radak: It is as if it said Al Beiso. We find like this - "El ha'Harim Lo Achal" (Yechezkel 18:6).
What is the meaning of "Hachel v'Chaleh"?
Rashi: It is to begin and finish. That day, My decree on Beis Eli will begin; Chofni and Pinchas will die. From now and onwards I will finish My decree from generation to generation to kill them "Anashim", i.e. 18 years old.
Malbim: That day Chofni and Pinchas will die, beginning the curse "Yamusu Anashim." It will finish with the other two curses in the days of David.
