Hausa Folk-Lore, by Maalam Shaihua, tr. by R. Sutherland Rattray, , at sacred-texts.com
This is a story about (a chief) Garnakaki.
A certain very powerful chief one day struck camp to go to war. He had a certain cook, (and) he had a wife, this chief, whom he loved. Everything the chief had was in this wife's possession. The cook was after this woman, and she also loved him, until one day the chief was secretly informed. The chief seized the cook (and) put him in prison.
Now he, the chief, was very fond of the cook, so he said he was to be taken out. He was taken out and brought forward. The chief said, 'In spite of all if you give up my wife, you may return and continue cooking food.' And he said, 'I shall. leave her.' Truly it was a lie.
Time went on, (and) he was cooking food for the chief. Of a truth they were together, (he) and this woman, (and) they were sinning against the chief, until (one day) they got medicine, (and) put it in the chief's food. The chief ate and died.
This woman took possession of much of the chief's property and much of the chief's money. She gave him (the cook) (them) secretly (and) no one knew, until they had finished taking everything. Then she came forward and married him. That was the origin of the saying, 'Love him who loves you, leave him who hates you, lest he give you medicine to eat (and) you die.'
Off with the rat's head.