Some one please tell me the story of Buddha said to some one how one should eat as if they are eating their own child having lost in a desert
It's in Puttanmansa Sutta.
"And how is physical food to be regarded? Suppose a couple, husband & wife, taking meager provisions, were to travel through a desert. With them would be their only baby son, dear & appealing. Then the meager provisions of the couple going through the desert would be used up & depleted while there was still a stretch of the desert yet to be crossed. The thought would occur to them, 'Our meager provisions are used up & depleted while there is still a stretch of this desert yet to be crossed. What if we were to kill this only baby son of ours, dear & appealing, and make dried meat & jerky. That way — chewing on the flesh of our son — at least the two of us would make it through this desert. Otherwise, all three of us would perish.' So they would kill their only baby son, loved & endearing, and make dried meat & jerky. Chewing on the flesh of their son, they would make it through the desert. While eating the flesh of their only son, they would beat their breasts, [crying,] 'Where have you gone, our only baby son? Where have you gone, our only baby son?' Now what do you think, monks: Would that couple eat that food playfully or for intoxication, or for putting on bulk, or for beautification?" "No, lord."
"Wouldn't they eat that food simply for the sake of making it through that desert?"
"In the same way, I tell you, is the nutriment of physical food to be regarded. When physical food is comprehended, passion for the five strings of sensuality is comprehended. When passion for the five strings of sensuality is comprehended, there is no fetter bound by which a disciple of the noble ones would come back again to this world.