Parshas BiShalach: Rav Yehonoson Eibshitz - Five Out Of Six Brothers Survived
"VaChamushim Alu Bnei Yisroel MeiEretz Mitzrayim" (Bishalach 13:18). Rashi offers two pshatim what this means. Either it means they went out of Mitzrayim armed and ready for war. Or it means that only one-fifth of the Bnei Yisroel went out of Mitzrayim with the others dying during Makas Choshech because they were not worthy of going out.
Rav Yehonoson Eibshitz offers another Pshat. He says that Chamushim means five out of six went out Mitzrayim. Where does he get this from? He explains that when in principle their should be no evil in the world. Everyone should be naturally bound to the word of Hashem. However Hashem created a Teva, a natural ebb and flow otherwise known as bechira which give a person the leeway to choose evil if he wishes.
This only applies to things Hashem created through Teva, but anything created L'Maala Min HaTeva through a Nes cannot do evil. Therefore since in Mitzrayim the women miraculously gave birth to six babies at a time, the one natural child can become a Rasha but the other five who were born through a Nes cannot. Therefore the one brother died while the other five, the Chamushim, safely left Mitzrayim.