We have a question on this verse.. When the verse says This is the line of Noah, it should then continue directly to teach us his descendants. Instead, there is an insert of something that seems out of place.. that Noah was a righteous man. So why does it say here are the descendants of Noah, without going straight into his actual descendants. What does this insert of Noah being righteous have to do with anything over here?
Let us preface what was written in the Holy book by the Holy Rabbi Rebbe Yehoshua of Belz, may his memory be a merit upon us. He comments on the below verse -
וּלְמַ֡עַן תְּסַפֵּר֩ בְּאׇזְנֵ֨י בִנְךָ֜ וּבֶן־בִּנְךָ֗ אֵ֣ת אֲשֶׁ֤ר הִתְעַלַּ֙לְתִּי֙ בְּמִצְרַ֔יִם וְאֶת־אֹתֹתַ֖י אֲשֶׁר־שַׂ֣מְתִּי בָ֑ם וִֽידַעְתֶּ֖ם כִּי־אֲנִ֥י יְהֹוָֽה׃
and that you may recount in the hearing of your child and of your child’s child how I made a mockery of the Egyptians and how I displayed My signs among them—in order that you may know that I am the LORD.”
The question asked on this verse is the following.. This verse is saying that you shall tell this story to your children and children's children, in order that you/we shall know that the Lord is G-D. The obvious question here would be that the verse should state 'in order that they shall know'.. since you are telling the children, shouldn't they be the ones that know, why are we the ones that know when the children are the ones being told? The Hebrew word in the verse should have been Vayedu, and not Vayedatem.
To answer we say that when a person wants to instill emunah/faith, and the oath of Torah into the heart of his friend, or child, he must first have emunah/faith himself. Any only then will his words leave from his heart, and enter the heart of another. However, if ones heart is not fully secure with trust in HaShem, then he/she will not have the power to instill the power of faith in HaShem to anyone else. So this is how we can explain/translate the above verse to be saying.. instead of "so that you may recount" we read it as "in order for you to be able to recount..." which means, in order for you to be able to teach emunah/faith to others... then what must you do? "..YOU must know", which means that you must know from the outset within yourself, and fully believe that "I am the Lord". And only then will you be able to instill faith in the hearts of others. Until here was his words.
We can take from his words that if someone wants his children or others to walk in the ways of HaShem, he himself must act that way and believe that way as well. It is not suffice for him to say to his son or others to go pray, or go study, if the father or the person himself trying to inspire, doesn't do those things himself. However, when a one is involved in Torah and Mitzvot, then his son, or others can receive from him and property act.
So here we have the intention of the opening verse of Noah.. 'These are the generations of Noah..'
When we want to know why Noah was worthy to have such great sons, the verse comes and teaches us, Noah was fully righteous. Since he was purely righteous, he was worthy that his children followed in his way. All the things he told to his sons to do, they did, and he himself did those same things that he instructed them to do. Therefor the verse doesn't go directly into listing their names by saying Shem, Cham, and Yafet right after it says here are the sons of Noah.. rather, the verse wanted to first let us know this principal, that in order for your children, or others to go in the path of HaShem, the father or teacher himself must be a Tzaddik/righteous, and then the verse goes on to continue listing their names, and this should be understood and comprehended well.