Today is the 7th day of Pesach, the day on which the sea parted and the Children of Israel crossed over from Egypt into the Sinai desert with Pharaoh's chariots in hot pursuit.
Tradition says that Nachshon ben Aminadav was the first to take a leap of faith and step into the sea. Only when the water was up to his neck did God part the Sea of Reeds.
Only then did the rest of the Israelites follow.
Here is how the midrash (Mechilta Beshalach 5) describes it:
“When Israel stood at the Sea, this Tribe said, ‘I will not be first to go down into the Sea;’ and the other Tribe said ‘I will not be first to go down into the Sea.’ In the midst of this argument, one individual, Nachshon ben Aminadav, Prince of the Tribe of Yehudah, seized the initiative, and went down first into the Sea, inspiring the rest of his Tribe to follow...For the deep meanings of Nachshon ben Aminadav's initiative, please take a look at "Courage and Risk" by Rabbi Nathan Lopez Cardozo and two of the Velveteen Rabbi's posts here and here.
At that moment, Moshe was deeply engaged in prayer. The Holy One, Blessed is He, said to him, ‘My beloved friends are drowning in the Sea, and you stand in Prayer before Me!’
Moshe said, ‘Master of the Universe, What should I do?’ He said to him, ‘Speak to the Children of Israel, and let them move...’ ”
For some humor, I give you a favorite cartoon about baby Moshe: