After Yosef reveals himself to his brothers, he sends them to inform his father that he is alive. He also sends with them wagons that contain all the bounty of Egypt.

He saw the wagons Yosef had sent to transport him, then the spirit of their father Yaakov was revived. (Bereishit 45:27)

Rashi (there) comments:

He gave them a sign, that which he was studying when he left him – egla arufa (the axed heifer), and this is what it says: "He saw the wagons (agalot) Yosef had sent."

This requires explanation: What is this sign that Yosef gave to his brothers, and why, as a result, "the spirit of their father Yaakov was revived"? It looks like there is some connection between the contents of this passage and Yosef's sojourn in Egypt.

Regarding the subject of egla arufa, the Torah says that when a corpse is discovered in the field and the killer remains unknown, the elders of the city nearest the corpse wash their hands in water at the place where the heifer is axed. They then say: "Our hands have not spilled this blood, and our eyes did not see." (Devarim 21:7) Chazal ask: Would it enter our minds that the elders of the court are murderers? Rather, that he did not come within our presence and we sent him off with no food, nor did we see him and leave him without escort. (Mishna Sotah 9:6)

We learn a very important rule from this passage. A person is responsible not only for actions with immediate results. He is also responsible for actions and deeds whose results only become apparent several years later, and only after a chain of events and occurrences that are derived from those actions. A murderer is not only the person who holds a gun and shoots people. He is also the person whose deeds caused a person to be killed in a distant time and place. Even more so, a murderer is also a person who, through inactivity, caused a person to lose his life. This we learn from egla arufa, that the elders of city say: "Our hands have not spilled this blood" – we did not send him off without food and escort. This means that if they had sent him off without food and escort, and it turned out that he ended up dead as a result – the elders of that city would not be able to cleanse their hands.

Food and escort are not necessarily material food and material escort. They can also be spiritual food and spiritual escort. When a person is sent on a mission that contains spiritual danger, it is necessary to check that he possesses the necessary tools to cope spiritually, because if, Heaven forbid, he ends up straying – it would be impossible to clean our hands.

Yaakov Avinu sent Yosef to Shechem, a place that is a source of trouble. There the tribes sinned, Dinah was tortured, and the kingdom of David was split. In that place there was not only physical danger, there was also spiritual danger. Yaakov was therefore obliged to supply Yosef with spiritual food and escort so that he would be able to cope spiritually with all the threats and dangers on the road. Therefore, he taught him the passage of "egla arufa" which is the sign of the spiritual food that Yosef had received for the road.

When Yosef sends to let his father know that he is still alive in Egypt, a place of spiritual contamination and idol worship, he sends him a sign that he remained the same person, and that he was on the same level of righteousness that he was in his father's house. This is the sign that Yosef sent to his father, that when he departed he studied the passage of "egla arufa." From this Yaakov knew that Yosef was still alive spiritually, and that the food and escort with which he supplied him at the beginning of his journey protected him from the contamination of the Egyptian culture. Therefore: "He saw the wagons (agalot) Yosef had sent to transport him, then the spirit of their father Yaakov was revived." When he witnessed the sign of "egla arufa" – the spiritual food and escort that he gave him, Yaakov was calmed. He knew that he succeeded with Yosef's education, and as a result he withstood the contamination of Egypt. Therefore: "the spirit of their father Yaakov was revived."

This responsibility is laid upon every one of us towards our children and students, to ensure that they receive spiritual food and spiritual escort which will accompany them throughout their lives, in order for them to handle all the events of life and remain steadfast in their path.