tznius

The Posuk in Parshas Vayetze (25, 29) says "Veheenei Hee Leah" and behold Yaakov woke up the next morning and beside him was Leah. Rashi says that Rochel showed her the "simonim" that were supposed to tell Yaakov that in fact it was Rochel not somebody else but when Lavan instead had Yaakov marry Leah, Rochel didn't want her sister to be embarrassed so she showed her the simonim. This is a Gemara in Megilah (13b). The Gemara says that "Bezchus Tznius Shehuysa BeRochel Zachsa Veyatza Mimenah Shaul".
בשכר צניעות שהית׳ בה ברחל זכתה ויצא ממנה שאול ובשכר צניעות שהיה בו בשאול זכה ויצאת ממנו א<ומאי צניעות היתד; בה ברחל דכתיב אםתר  ויגד יעקב לרחל כי אחי אביה הוא וכי אחי אביה הוא והלא בן אחות אביה הוא אלא אמר לה מינסבא לי אמרה ליה אין מיהו אבא רמאה הוא ולא יכלת ליה אמר לה >א< אהיו אנא ברמאות אמרה ליה ומי שרי לצדיקי לםגויי 3 עם נבר תתבר ועם ברמיותא אמר לה אין עקש תתפל אמר לה ומאי רמיותא אמרה ליה אית לי אהתא דסשישא מינאי ולא 5 ׳מסר לה סימנים כי מטא מנםיב לי מקמה ליליא אמרה השתא מיכספא אחתאי 4 ויהי בבקר מםרתינהו ניהלה והיינו דכתיב והנה היא לאה מכלל רעד השתא לאו לאה היא אלא מתוך םימנין שמסרה רחל ללאה לא הוה ידע עד השתא לפיכך זכתה ויצא ממנה שאול ומה צניעות היתה בשאול 5 ואת דבר המלוכה לא הגיד לו אשר דכתיב אמר שמואל « זכה ויצאת ממנו אסתר

The obvious question is that it was a very altruistic deed but why does the gemarah call it tznius? furthermore why is Shaul the ultimate reward and not any of the other great people that were descendants of Rochel from either Shevet Yosef or Binyamin?

We can explain the concept of Tznius in a new light. The word is "Discretion". Rashi says on the gemarah that it was tznius of Rachel that  ללאה והוא צניעוח שלא יתפרסם הדבר שמסר לה סימנין: She was secretive about the simonim. Sometimes you have to keep things very quiet and sometimes you have to reveal things even if is at the cost of self sacrifice.

Shaul had a similar situation in that he wanted to tell people that he was made king but "Et Dvar Hamlucha Lo Higid" and that was his discretion that he did NOT tell anybody about the fact that he became king. Rochel told Leah, Shaul told nobody they both had discretion when and when not to say something and that seems to be the meaning of Tznius in this context.

That might explain why Bezchus Tznius of Shaul Zacha Veyatza Mimenu Esther. Esther was in a similar situation. First when she did not tell anybody her nation or her birthright and even moreso when it came time to speak with King Achashverosh, she didnt want to say anything for fear of getting killed and Mordiechai told her that she must and she did so risking her life. She kept silent when she was meant to and spoke with discretion when she had to.

Another aspect of Tznius is possibly the aspect of seeing things one dimensionally. Rochel could have felt that if she gives the simonim to Leah then she would lose her husband because if Leah married Yaakov then she would not get to mary Yaakov. However she realized that if you have real emunah things are not necessarily zero sum. She did what she had to do so that her sister wouldnt be embarrassed.  She had to believe that whatever God had in store for her she would get, her job was to do what was right. Life in a society is not a competition. If on understands that and internalizes that they won't show off to others and won't feel the need to show that they are better than others and that is where our idea of Tznius comes from. Our existence is directly related and connected to our connection with God and others don't play a role. Being ostentatious would indicate a feeling of "I'm better than the next guy" or richer, prettier, better, etc. if one had the right attitude there is no place in existence for those type of feelings.
 
Because Rachel lived like that therefore her reward was in fact that her descendant was Shaul hamelich the first king of israel. Midah keneged midah. the king is in fact the person who is greater than the rest and his reward was esther who also became queen and ruled with Achashverosh over the whole world.