C. F. Keil and Franz Delitzsch on Ecclesiastes 4:11

Ecc 4:11 “Moreover, if two lie together, then there is heat to them: but how can it be warm with one who is alone?” The marriage relation is not excluded, but it remains in the background; the author has two friends in his eye, who, lying in a cold night under one covering (Exo 22:26; Isa 28:20), cherish one another, and impart mutual warmth. Also in Aboth de-Rabbi Nathan, c. 8, the sleeping of two together is spoken of as an evidence of friendship. The vav in vehham is that of the consequent; it is wanting 10 a, according to rule, in haehhad, because it commonly comes into use with the verb, seldom (e.g., Gen 22:1) with the preceding subj.