No One is Left Behind

On Shabbos, Parshas Beha’alosekha, Rav Dovid Cohen spoke about the pasuk:
And Miriam was shut out from the camp seven days; and the people journeyed not till Miriam was brought in again.
--Bamidbar 12:15

Rashi says: This honor was given to her by Hashem because of the time she waited for Moshe after she cast him into the Nile, as it says, And his sister stood far away, to see what would be done to him (Shmos 2:4).

The Gemara in Sotah 9b
MIRIAM WAITED A SHORT WHILE FOR MOSES, AS IT IS SAID, AND HIS SISTER STOOD AFAR OFF; THEREFORE ISRAEL WAS DELAYED FOR HER SEVEN DAYS IN THE WILDERNESS, AS IT IS SAID, AND THE PEOPLE JOURNEYED NOT TILL MIRIAM WAS BROUGHT IN AGAIN.

Yalkut Shimoni interprets “the people journeyed not till Miriam was brought in again”
to mean that HKBH prevented the people from traveling by holding back the Aron, the Shechina, Kohanim, Leviyim, Yisraelim and the seven clouds of glory.

The Israeli army has a policy that no soldier is left behind. Even if an entire regiment is at risk they do not leave until that soldier is brought with them.

What is the basis for this? Is it halakhic?

The Tzitz Eliezer discusses this question. Normally, an individual is not obligated to put his life at risk for someone else. During war a society’s prerogative and obligation is to protect its soldiers and may take on an obligation that is a midas chasidus, an act of piety.

This practice of the Israeli army as a community at war is lifnim mi’shuras ha’din and, therefore: No one is left behind.

Rav Dovid Cohen has a regesh, a feeling, that the act of Miriam keeping an eye on Moshe’s welfare at the Nile inculcated this midah of chasidus into our tradition. So, midah k’neged midah, she was repaid and we are the beneficiaries of her midas chasidus becoming part of our tradition as a nation.