Thus regretted and cautioned on all hands, he took leave of the hospitable household. 

regretted and cautioned on all hands，是过去分词短语作原因状语，逻辑主语是 he，表被动。可以转换为原因状语从句：

Thus because he was regretted and cautioned on all hands, he took leave of the hospitable household. 

意思是：因大家对他感到遗憾（惋惜或难过），而且受到了大家的告诫，所以他告别了那好客的一家人走了。

on all hands，习语。指 “大家全体，四面八方”。