(taken from the thread in general and posted here as the resident Pali experts may be more likely to notice it)
"As a mother would risk her life
to protect her child, her only child,
even so should one cultivate a limitless heart
with regard to all beings." (trans. Thanissaro)
In a dhamma talk by Ven Thanissaro he mentioned that the phrase mentioned above refers not to the quality of the metta, but to the care and protection put into cultivating the metta itself.
"Some people misread this passage—in fact, many translators have mistranslated it—thinking that the Buddha is telling us to cherish all living beings the same way a mother would cherish her only child. But that’s not what he’s actually saying. To begin with, he doesn’t mention the word “cherish” at all. And instead of drawing a parallel between protecting your only child and protecting other beings, he draws the parallel between protecting the child and protecting your goodwill. This fits in with his other teachings in the Canon."
What do those here knowledgeable about Pali say?
"If beings knew, as I know, the results of giving & sharing, they would not eat without having given, nor would the stain of miserliness overcome their minds. Even if it were their last bite, their last mouthful, they would not eat without having shared."