The healer was a most respected person in traditional times as they were gifted with the art and wisdom of healing with herbs. This required knowledge that was passed on from generation to generation and in some cases given through forms of divination. Because of these healing powers and sometimes powers to perceive what others could not perceive they were sometimes even feared and as such few would challenge their thinking. However even the most respected healer would seek another healer if s/he fell ill or there was trouble in their homestead. In other words they were incapable of healing themselves or practicing on themselves. This led to our elders observing that an individual cannot be expected to be partial in a case in which they are involved in and would hence have to seek the views of others.
The proverb used to advice on the importance of one not being a judge in their own case but to rather listen to others views. It is also used to exonerate someone from taking up a role that is compromised by their involvement in the same issue.