Then Klal Yisrael sang this song: "'Ascend, O well,' sing to it! (21:17) The Kli Yakar notes, since it only says that the Yidden said praise, and not Moshe also, it is evident that this praise came from Klal Yisrael alone and not from Moshe! The question is: What spurred the Yidden to say Shirah now?
The Daas Zekeinim Baalei Tosfos, a commentary from the Rishonim in the Chumash, says a powerful insight which we learn a super lesson. He says: At that point Klal Yisrael broke out in a song of thanksgiving; when the people took possession of this well their hearts were full of gratitude, “dgny jezn". They were full of Simcha as they had previously been afraid of if not dying from thirst themselves, their livestock dying due to a shortage of drinking water. This well was not like the other wells which supplied a steady amount of water, but it increased as time went on so that it was easily accessible even when the Israelite crossed elevations in the ground on their way.
The Baal Haturim says an insight which adds to the previous insight: We find twice the word Ep¡r in Tanach. Here it says D« ̈l "Ep¡r" x−¥` §a i¬¦l£r and in Tehilim it also says E ́p¡r d® ̈c ez §a 'd«©l this proves that at the well they said thank you to Hashem, The thank you was the Shirah.
This teaches us when a person realizes that Hashem is good to him and acknowledges it, he should say thank you Hashem, and say a praise or Shirah. We actually do this every day at davening. :D ̈wEl §l «©d D ̈w l¬¥N ©d §Y d ̈n ̈W §P †©d l ́ M Let all that breathes praise Hashem (Tehilim 150:6). The Midrash Devarim Rabbah 2:37 says the Torah states: (Devarim 6:5) “You shall love Hashem with all your heart, with all your soul, and with all your might”. Rabbi Mayer said: For each and every breath that a person takes, he is obligated to Praise, glorify his Creator. From where is this derived? As it is stated: “Let everyone who breathes praise Hashem”. Now that we meditate and realize that Hashem has given us life and we can breath, we follow with saying a praise to Hashem:
Blessed is Hashem forever, Amein and Amein! Blessed is Hashem from Tzion, Who dwells in Jerusalem. Praise Hashem. Blessed is Hashem Who alone performs wonders. And blessed is the Name of His glory forever, and may His glory fill the whole earth. Amein and Amein!
The great Gaon and Tzaddik Rav Avigdor Miller, opened our eyes to notice all the small things in life, and to thank Hashem for all. The railings, the umbrella, even the color of the fruits, all these are for us, and we have to thank Hashem for them. This should bring Simcha to us, and we are ever obligated to the Chesed Hashem does with us constantly. We are also obliged to say Shirah and praise Hashem with saying thank you.
The same idea is when we recite the prayer of Ep §g«©p £` mi ¦c K ̈l in Shemona Esrai: We give thanks to You and recount Your praise, for our lives which are committed into Your hand, and for our souls which are entrusted to You, and for Your miracles of every day with us, and for Your wonders and benefaction at all times— evening, morning and noon. Then the following prayer is the praise and Shirah:
And all the living shall thank You forever and praise and bless Your great Name with sincerity forever; for You are goodness— the Almighty.
This gives a different light when we say these prayers. We must dwell, and think deeply into all the Chassadim that Hashem does with all of us constantly. All Hashem wants, is to praise and thank Him. When our davening is with Kavanah, we see and realize the greatness of Hashem. This brings out the inner happiness and Simcha, which brings us closer to Hashem, and serve Him with Simcha.