Positive commandment · Mitzvat Aseh #202 of 613
To assist a colleague in unloading a burden which he or his beast [is carrying]
לעזוב מעל חברו או מעל בהמתו
The verse · Shemot 23:5
כִּי־תִרְאֶה חֲמוֹר שֹׂנַאֲךָ רֹבֵץ תַּחַת מַשָּׂאוֹ וְחָדַלְתָּ מֵעֲזֹב לוֹ עָזֹב תַּעֲזֹב עִמּוֹ
“If thou see the ass of him that hates thee lying under its burden, and wouldst forbear to unload it, thou shalt surely unload it with him.”
The Rambam’s words
To assist a colleague in unloading a burden which he or his beast [is carrying], as [Exodus 23:5] states: "You shall surely help him."
לעזוב מעל חברו או מעל בהמתו, שנאמר: "עזוב תעזוב, עימו" (שמות כג,ה).
Why · Sefer HaChinuch #80
Removing a burden
“It is from the roots of the commandment to train our souls in the trait of compassion, which is a praiseworthy trait. And there is no need to say that there is an obligation to have compassion on a person in pain in his body.”
Who & when
“And [it] is practiced in every place and at all times by males and females.”
Where in the Mishneh Torah
Hilchot Murderer and the Preservation of Life הלכות רוצח ושמירת נפש