Is there a biblical origin for shomer negiah?
I am still in my learning. Thanks.
There is no need to be embarrassed or apologetic for wanting to learn! Wanting to learn and not being embarrassed to ask questions is being intellectually honest, and the only way to grow.
Regarding your question, the same way that it is forbidden to have an intimate relationship with a woman that is forbidden to us, it is also forbidden to touch them. This is learned from the verse (Leviticus 18 verse 6 & 19) “To a married woman don’t get close to exposing ervah” “To a woman that is nidah don’t get close to expose ervah”. The understanding of not getting close (among other things) means not to touch. This is the biblical source according to Maimonidies (Isurei Biah 21-1), that we may not touch any woman prohibited to us in a way that can lead to anything immoral.
As a side point, the term “shomer nigiah” can be misleading. It can have a connotation that it is only optional, as if one may choose to be careful with it if they so choose, similar to being “cholov Yisroel”. However this is not true. It isn’t a “chumra”, rather a clear biblical prohibition. Therefore the term “shomer negiah”, would be more similar to “shomer shabbos”, in the sense that both of them are serious biblical commandments.