There is a well known Midrash concerning Eliezer’s quest to find a wife for Yitzchak. We are introduced to Rivka’s family and are told her father’s name was בתואל and her brother was לבן.
When Eliezer is brought to Rivka’s house, we find לבן doing all the talking. The Rabbis comment that he was disrespectful by not letting his father speak first.
We never hear from בתואל again. Rabbeinu Bechaye pointed out that there is unusual wording in the Pasuk. It says ויושם לפניו לאכול, that food was placed before him to eat. This awkward wording of ויושם, to place, was a hint to what actually transpired.
The word סם in Hebrew means poison. This is where it is learned that Lavan and Betuel tried to poison, “סם”, Eliezer in order to steal his money. An angel switched Eliezer’s plate with Betuel’s and that is why we never heard from him again!