Phrases.org quotes Robert Forby in his glossary The Vocabulary Of East Anglia, 1830, commenting that the entry falls short of mentioning the actual wording 'bone-idle' :
Bone-lazy, bone-sore, bone-tired, adj. so lazy, sore, or tired, that the laziness, the soreness, or the fatigue, seem to have penetrated the very bones.
1593 G. Harvey Pierces Supererogation 185 Was..legierdemane a sloweworme, or Viuacitie a lasie-bones.
1600 N. Breton Pasquils Mad-cap (Grosart) 12/2 Go tell the Labourers, that the lazie bones That will not worke, must seeke the beggar's gaines.
1836 T. Carlyle New Lett. (1904) I. 8 For the last three weeks I have been going what you call bone-idle.
1891 R. Kipling Light that Failed vi. 98 Bone-idle, is he? Careless, and touched in the temper?
I am intrigued as to how bones can be either 'lazy' or 'idle'. It is muscles that are the active constituents of limbs. Bones are moved by muscles.
Is the origin due to the concept of just the depth of idleness, that there is nothing deeper in a limb than a bone ?
Or is there some other original meaning to the idiom ?
Note : There is a mention of 'bone idle' in an answer to a closed question but the answer gives no information about the origin of the expression.