Ecclesiastes 4:11
Again, if two lie together, then they have heat: but how can one be warm alone?
Cross-reference
1 Kings 1:1
Parallel
1 Kings 1:1 describes elderly David unable to get warm despite being covered — a literal illustration of the problem of keeping warm alone.
1 Kings 1:2
Parallel
1 Kings 1:2 provides the solution: a young woman lies in David's arms to warm him — directly applying the two-lying-together principle.