Behold, I will send you Elijah the prophet before the great and awesome day of the LORD comes. (Malachi 3:24 [English 4:5]; ESV)
According to the synagogue calendar, the Sabbath before Passover (Passover this year begins the evening of April 8) is a special Sabbath called "Shabbat Hagadol" (the Great Sabbath). Shabbat Hagadol commemorates God's command four days before the first Passover in which all Israelite households were to take into their homes the lamb they would slaughter.
Effectively fulfilling a task often requires significant preparation. Whether it be a meal, a trip, a test, or a meeting, neglecting sufficient preparation almost certainly guarantees failure. Good preparation, on the other hand, is basic to success. Note that preparation is not just about being aware of the future task. Worry requires awareness, but produces nothing of value. Similarly just busying oneself in the name of preparation doesn't do any good. Effective preparation requires appropriate and thorough attention to whatever might be required in advance of the future task.
The chapter in which this week's special Haftarah reading for Shabbat Hagadol is found speaks of preparation. It tells of how God would send a messenger, Elijah, who will prepare the way before him. This is like when a dignitary or celebrity sends an advance team prior to his arrival to ensure that everything is ready before he arrives, so that when he does arrive he is able to most effectively accomplish the desired outcome.
Effective preparation puts us in a state of readiness. In this passage, God whose way was to be prepared before him, would arrive suddenly. This suggests that even though preparations would be made, God's arrival would still be somewhat unexpected. This makes the preparations that much more important. In order to receive God's coming properly the people would need to be prepared and remain prepared. A picture that comes to mind is of getting a fancy dinner ready for very important guests and then having to wait for their arrival. We know they are coming, but we don't know exactly when. As the minutes go by, we wonder if something may have gone wrong. At that point we have the choice to either keep everything prepared as is, so that everything will be as it should be when they arrive, or we can go on with the dinner without them and risk the embarrassment of their arrival, no longer prepared as we should be. Worse than that, we may give up on waiting altogether and miss their arrival.
Celebrating Passover is the reminder of God's provision of a lamb so that his people could escape his judgment and be set free to journey to the Promised Land. Sufficient preparation was absolutely necessary to ensure the people's participation in their deliverance. Passover is also the reminder of God's provision of another Lamb - the Messiah - whose preparation was spoken of by the prophet. Sadly many were not prepared for his sudden arrival. Now we prepare for his return. The words of the prophet remain relevant, but how long before he returns, we don't know. Yeshua is coming again, let's be prepared.