In this week's Parsha the Jews witnessed the great miracle of the splitting of the sea and sang 'Az Yashir' written in this week's Parsha and what we say every morning by Shacharis.
However, the Passuk tells us that this was sung by the men. After the men finished, the women led by Miriam, Moshe Rabbeinu's older sister, also sang praises. The woman sang one phrase from the Az Yashir, "Sing to Hashem as He is highly exalted, He threw the horses and their riders into the water."
Why did Miriam choose this Passuk more than everything else the men had sung?
Rabbi Yaakov Kamenetzky explains with a beautiful insight. Miriam was trying to teach the Jews a very important message.
The Gemarah tells us that Hashem's punishment to the Egyptians was exact. The most wicked ones sunk like straw, thrown around up and down. Those that were not so wicked, sunk like stone, and the the one's that deserved the least pain sunk like lead. If Hashem is so exact with his judgement, why did the horses drown, they hadn't sinned at all?
The answer is that they were partners in chasing after the Jews, they helped the Egyptians to run after the Jews.
The Jews merited to be saved from Egypt in order to receive the Torah at Har Sinai. But that is a good reason for the men. What about the women? Miriam had the answer.
In the same way that the horses were punished as partners with the Egyptians, so too the women are partners in their husband's and children's study. They cook, wash and do all the household chores that help their husbands and children to study Torah.
If the horses were punished as partners in crime, so too the women will receive reward as partners in the Torah study of the men.
With this explanation we can understand the Passuk in Shir Hashirim (1-19) "to my horse in the chariots of Pharaoh, you, my wife are compared to." Our wives and mothers will merit a full share in our Torah study thanks to the horses of Pharaoh at the sea.
