Prior to giving Gad and Re'uven land on the East side of Jordan River, Moses makes them keep a condition:
Numbers 32:20-22:
וַיֹּ֤אמֶר אֲלֵיהֶם֙ מֹשֶׁ֔ה אִֽם־תַּעֲשׂ֖וּן אֶת־הַדָּבָ֣ר הַזֶּ֑ה אִם־תֵּחָֽלְצ֛וּ לִפְנֵ֥י יְהוָ֖ה לַמִּלְחָמָֽה׃ וְעָבַ֨ר לָכֶ֧ם כָּל־חָל֛וּץ אֶת־הַיַּרְדֵּ֖ן לִפְנֵ֣י יְהוָ֑ה עַ֧ד הוֹרִישׁ֛וֹ אֶת־אֹיְבָ֖יו מִפָּנָֽיו׃ וְנִכְבְּשָׁ֨ה הָאָ֜רֶץ לִפְנֵ֤י יְהוָה֙ וְאַחַ֣ר תָּשֻׁ֔בוּ וִהְיִיתֶ֧ם נְקִיִּ֛ים מֵיְהוָ֖ה וּמִיִּשְׂרָאֵ֑ל וְ֠הָיְתָה הָאָ֨רֶץ הַזֹּ֥את לָכֶ֛ם לַאֲחֻזָּ֖ה לִפְנֵ֥י יְהוָֽה׃
And Moses said unto them: ‘If ye will do this thing: if ye will arm yourselves to go before the LORD to the war, and every armed man of you will pass over the Jordan before the LORD, until He hath driven out His enemies from before Him, and the land be subdued before the LORD, and ye return afterward; then ye shall be clear before the LORD, and before Israel, and this land shall be unto you for a possession before the LORD.
Then, we see in verse 33, that when Moses gives the land, he includes part of the tribe of Menashe. But, we don't explicitly see that they were bound by the same oath that Re'uven and Gad was. Did they have to take the same oath or be bound by the same conditions? If not, why not?