1)
It already said "Nisuni". Why does it say "Bechanuni"?
1.
Rashi: They tested Me for no reason.
2)
Why does it say "Gam"?
1.
Radak: After seeing Him take them out of Egypt with great wonders, He also split Yam Suf, brought down manna, and split the rock [to give water].
2.
Malbim: This shows that they had a hard heart - they tested Him even after seeing His wonders, and that He constantly engages in supplying their needs, to benefit them!
3)
When did they see His actions?
1.
Rashi: In Egypt.
2.
Radak: Before testing Hashem, and after.
