A serious change took place with the Jewish people.
In Egypt, Moshe had observed that the people he was to lead were a difficult people. He had seen Jews beating each other and informing on each other. He was frustrated by how they didn't get along, and complained to Hashem about their lashon hara and their whining. He was worried that their negative nature would prevent the redemption. (Rashi Breishis 2; 14)
However, by the time they arrived at the foot of Mount Sinai, the Torah reports that they were “like one man with one heart”. They were completely united. How did they achieve this unity? How did they go from being petty slanderers to a people united? What transformed them from critical and whining to loving and brotherly?
The answer is, that it was not their unity that brought about the Torah — it was the Torah that gave them unity!
The people of Israel were petty because their lives were petty. They had no goal and they had no vision. They worried about small stuff because there was no larger picture. They were obsessed with the moment because they didn't see a future. When they realized in their hearts that there was a larger purpose, the paltry issues were shed. Deciding to accept the Torah gave them a sense of purpose and mission. When one has a mission, the little things just don't matter. At the foot of Mount Sinai, at the threshold of greatness, we found a new perspective. We got a life, and we all became one.
Let's test ourselves. If we find ourselves acting in a petty way, if we find that inconsequential things bother us, if we find ourselves so touchy that we draw a wedge between ourselves and the people we love the most, we are probably missing the big picture.
Even after the great epiphany at Mount Sinai our people began to bicker again. They forgot the big picture. They lost their awareness. They had to recreate Har Sinai over again, as do we. This time from the inside, and this time, with G-ds help, the big picture will get even bigger.