What is "mi'De'agah mi'Davar"?
Rashi: It is due to fear.
Why were they concerned lest children of Eretz Yisrael proper will say so?
Malbim: The Yarden separates us, and many Mitzvos do not apply to Chutz la'Aretz. 1
Chachamim say that we bring Bikurim from Ever ha'Yarden (Bikurim 1:10). R. Yosi ha'Gelili exempts, for it is not "Zavas Chalav u'Devash." Some exempt due to "Asher Nasati Li", and not what I took for myself (Yerushalmi Bikurim 1:8). Tashbatz (3:198)