The Gemara in Shabbos 113b says on the possuk in Mishlei תן לחכם ויחכם עוד and on this posuk Rabbi Elazar says this is Rus and Shmuel. Apart from what the proofs the Gemara brings. I want to know why specifically these two people, which is based on a verse that could seemingly be anyone else?
The both did something outstanding. Most wise people can extrapolate from a given set of commands how to extend the concept. This is taken from the simple reading of the pasuk.
The Ein Yaakov (Shabbos 113- "תן לחכם") cites that based on "ראשית חכמה יראת ה" they both based their wisdom (חכמה) on יראת ה and not mere wisdom. That is unique and thus the R' Elazar is singling them out.
Rus was careful not to first wash and bedeck herself and then go to the fields of Boaz so she wouldn't cause theh workers there to sin (be נכשל) when seeing her that way so she reversed the order by first going to the field and then washing up and dressing up later.
Shmuel was extra careful how he chose his words so he wouldn't say Hashem's name needlessly should the voice turn out not to be Hashem calling him.
In both cases it was fulfilling the pasuk in a unique way. So they get special mention.