Imaam Mujaahid (rahimahullah) mentions that Hazrat Abu Hurairah (radhiyallahu ‘anhu) would say:

I swear by that Being besides whom there is no other deity that quite often, overwhelmed with hunger, I would lay my chest and stomach onto the ground (so that the moisture and coolness of the ground may alleviate the heat of my hunger to some extent). Occasionally, I would fasten a stone to my stomach merely to keep my back straight.