1) In the Mishnah in Pirkei Avos 1:6, Yehoshua ben Perachyah advises us, "Acquire a friend for yourself." Rabeinu Yonah writes that a person needs a good friend for three reasons:

a) To learn Torah together.

b) To do Mitzvos together. Even if his friend is not of a better character than himself, still, neither of them wants to see the other doing bad things, so they will do Teshuvah together.

c) Someone he can help, and his friend will help him in return. He can confide in him and share secrets. They will be able to give each other advice when they need it.

2) The commentary Yosef Lekach writes that this is why the Rambam (Hilchos Eruvin 6:6) writes that it is a Mitzvah to meet one's friend, since it is a Mitzvah to have a friend! The friendship will be strengthened if you meet a friend when he comes in from a journey. Everyone is happy to have someone meet him off the plane or the train!

3) The Mishnah Berurah (415:3) writes that this Mitzvah applies whether or not his friend is a scholar, although he does mention an opinion that the friend is required to be a Chacham.

4) According to the Rambam, the Heter for Eruv Techumim applies only if one is meeting the friend when he is coming from a journey.

5) I think it is important to know that this is not the only place in Halachah where Re'iyos Penei chavero is considered a Mitzvah which gives us a Heter to do things which otherwise we may not do.

a) There is another example in Shulchan Aruch, Hilchos Shabbos, Orach Chayim 248. The issue there is embarking on a sea journey before Shabbos. One may not embark on a journey within three days before Shabbos, because during the first three days of the journey one is sea sick and uncomfortable and as a result will not experience Oneg Shabbos on Shabbos. However, if one is traveling for a Mitzvah, he is permitted to leave even on Friday. The Rema (end of OC 248) writes that some say that if one is going to meet his friend, this is considered a Mitzvah. The Tur there writes that this is the opinion of Rabeinu Tam. The Beis Yosef writes that not all authorities agree with Rabeinu Tam, but the Rema writes that one should not rebuke people who are lenient with this, because there are opinions in HalachaH on which they are entitled to rely.

b) Another example is in Shulchan Aruch, Hilchos Chol ha'Mo'ed, Orach Chayim 551:4. The issue there is which people are allowed to take a haircut on Chol ha'Mo'ed. If somebody had been overseas and arrived back home only on Chol ha'Mo'ed, or arrived so close to Yom Tov that he did not have time for a haircut before Yom Tov commenced, he may cut his hair on Chol ha'Mo'ed. However, the Shulchan Aruch writes that this Heter does not apply to someone who went from Eretz Yisrael to Chutz la'Aretz for a pleasure trip. In the latter scenario, it is not considered that he has permission to leave Erertz Yisrael, but the Mishnah Berurah (#14) writes that if he left Eretz Yisrael in order to meet his friend, this is considered a Dvar Mitzvah for which one is permitted to leave.

(In this case, nobody seems to disagree or say that it is only permitted if the friend is a Chacham.)

c) I would like to suggest that the Heter in the above three areas of Halachah for Re'iyos Penei Chavero may be based on the Gemara in Ta'anis, end of 23a, which tells us the popular saying, "O Chavrusa O Misusa" -- "either a Chavrusa, or death"; if one does not have a Chavrusa one may as well die. If a person is not honored by his friends, he would prefer to die.

I suggest that this is why one is allowed to make an Eruv Techumim to enable visiting a friend; the honor that the friend gets from this really revives him.

6) Here is a more reliable source:

a) The Mishnah Berurah, in Sha'ar ha'Tziyun 415:9, writes that when one's friend is coming from a journey, the Mitzvah to meet him is included in She'eilas Shalom and Kavod ha'Beriyos.

b) The Mitzvah of She'eilas Shalom is a Mitzvah of Darkei Shalom, to behave in a peaceful way with others. See Pnei Yehoshua to Berachos 27b, who says that the chief purpose of She'eilas Shalom is that this represents a prayer that a friend should be at peace.

c) Kavod ha'Beriyos is giving honor to our friends. There are many different levels of Kavod ha'Beriyos. Rashi (Berachos 19b, DH ud'Ka Kashya) writes that one is permitted to violate a rabbinical prohibition for the sake of Kavod ha'Beriyos (for example, if someone is walking on Shabbos in a place where carrying is prohibited mid'Rabanan and he finds out that his Tzitzis are Pasul, he is not required to take off his Tzitzis because of the embarrassment involved, even though wearing Tzitzis that are Pasul is considered as though he is carrying the garment).

From the aforementioned Sha'ar ha'Tziyun we learn that when someone arrives from a journey, it gives him honor to go and meet him, and a certain leniency may be made in order to give oneself an extra 2,000 Amos of walking on Shabbos by making an Eruv Techumim.

Kol Tuv,

Dovid Bloom