This Mishnah presents another dispute between Chanan and the sons of the High Priests, and it concerns a person who supported another man's wife while the husband was away.
The case in the Mishnah:
The husband traveled overseas.
A third party came forward and supported the wife on his own initiative.
No one had asked him to do so, and the wife herself did not borrow any money from him for her support.
Chanan's position:
When the third party later comes to collect his money, Chanan rules that he has lost it: neither the husband nor the wife is obligated to repay him. However, had the wife actually come and borrowed money from him, the husband would have been obligated to pay off the debt.
The position of the sons of the High Priests:
The sons of the High Priests disagreed with Chanan and held that the man who supported the wife "yishava kamah hotzi v'yitol" - he takes an oath as to how much he spent and collects it, meaning he may recover his expenses from the husband, provided he swears to the amount he laid out.
Rabbi's opinion:
Rabbi ruled in accordance with Chanan, that the third party cannot collect, and he compared such a person to one who "hiniach me'osav al keren hatzvi" - placed his money on the antler of a deer, a place that offers no security whatsoever. Even if the money were to stick to the antlers, it is exceedingly difficult to catch the deer; so too, one who spent his money on his own initiative is considered to have lost it.