How could Yosef instuct his overseer to bring his brothers back and thus delay them, when his father was living in the grip of a famine?

(44,4) "They went out from the city, they had not gone far, and Yosef said to the overseer of his house: Arise, chase after the men, and when you reach them say to them - Why have you repaid evil for good?"

The Midrash, which is brought in the Yalkut, explains "they had not gone far" (לא הרחיקו) - as it says in Yehoshua (3,4) "there should be a distance (רחוק) between you and it of two thousand cubits". This Midrash is very puzzling.

But behold, it says in the Midrash on the posuk (43,16) "and slaughter an animal והכן (and prepare)", that this took place on Erev Shabbos, because the word והכן signifies preparation for Shabbos, as the posuk in Shemos (16,5) says "and it will be on the sixth day and they will prepare (והכינו) that which they will bring". But this raises a problem, because this would mean that the brothers' return trip the following day - "the morning became light, and the men were sent on their way" (44,3) - took place on Shabbos morning. How could the tribes have profaned the Shabbos by travelling on it? We have to answer that they were permitted to do so because Yaakov and his houshold were in danger of starvation because of the famine, as we see from the way Rashi explained the posuk (42,1) "why should you appear so?" - why should you become thin from the famine? And when there is a danger to life the laws of Shabbos are pushed aside.

But this creates a difficulty with the behaviour of Yosef, because he knew that his brothers were travelling on Shabbos, and he must have known that they would not have done so unless there was a danger to life. If so, how could he have instructed his overseer to bring them back, and not be concerned about his father and his father's household who were in the grips of a famine?

But maybe the correct explanation of the posuk "why do you appear so?" is like the other explanation of Rashi - why do you appear in front of the children of Yishmael and the children of Eisav as if you are satiated, because at that point in time they still had some produce. Thus, Yosef saw that the faces of his brothers were happy and that they had the appearance of wealthy men, as it explains in the Yalkut, and from this Yosef learned that they still had produce at home. And Yosef would have understood that although they had left the city, they had not gone beyond the two thousand cubit limit that it was permitted for them to go on Shabbos. And the reason why they had left at all was because Yosef, whom they still had not recognised, had spoken harshly to them, so they wished to give the impression that they had left in order to avoid giving Yosef a further opportunity to speak harshly to them.

But Yosef wanted to arrive at the truth, to know whether they had produce in their home or not, and so which explanation of the posuk "why do you appear so" was the correct one. Therefore, he commanded his overseer to arise and pursue them. That is, he instucted him that if he should see from a distance that they have not gone beyond the two thousand cubits, then this would prove that there is no danger to life, and therefore he should pursue them. But if he sees that they have gone beyond this, then it is clear that there is a danger to life, and so he should not pursue them.

Now the Midrash that we first brought, which explained that "they had not gone far" means that they had not travelled two thousand cubits, is clear, because this was the sign that Yosef gave to his overseer which would determine whether he should pursue them or not.