Just a few weeks ago, Klal Yisrael experienced many miracles and salvations. Through great nisim, Hashem saved them from powerful missiles. We mustn't forget, and we mustn't attribute it to nature. We have to continue praising Hashem for the miracles that occurred, which saved so many lives of Bnei Yisrael.
The Alshich HaKadosh (Vayikra ch.7) teaches that if לְהוֹדוֹת צְרִיכִים א ַרְבָּעָה, "Four must praise Hashem", because their lives were in danger, and Hashem saved them, certainly those who Hashem spared and were never in danger in the first place must praise Hashem. They are even more obligated to praise Hashem because Hashem gave them His kindness, without them experiencing any worry or distress.
A similar explanation: Everyone should praise Hashem. There are so many things to be thankful for. Even for the basics, like life, health, etc., are sufficient reasons to praise Hashem constantly. However, people lose sight of this. However, when a miracle occurs to them, then they praise Hashem. Sometimes, Hashem brings an illness, an imprisonment, or some other trouble, and the purpose is לְהוֹדוֹת צְרִיכִים, so people will praise Hashem. They weren't doing so until now, and now, when they praise Hashem for the miracles, they will remember to praise Hashem for all the other kindnesses Hashem constantly performs for them.
The Or HaChaim (8:18) writes, "The yetzer hara's first ploy is to cause people to forget [Hashem's kindness], and this destroys them. This can be the translation of the next pasuk, שכוח אם והיה, 'If you will forget that Hashem does kindness to you, אלקיך 'ה תשכח, you will forget Hashem...'
Reb Shmuel Tchuliner zt'l (a student of Reb Moshe of Kobrin zt'l) once experienced a chesed from Hashem, and he didn't stop speaking about it. His family asked him why he kept repeating the same story. Reb Shmuel replied, "The Or HaChaim says 'The yetzer hara's first ploy is to cause a person to forget Hashem's kindness,' therefore I'm repeating it many times so that I won't forget."
Similarly, we were receivers of Hashem's miracles, and we must not forget them.
It states (Bamidbar 21:27) בֹּאוּ הַמ ֹּש ְׁלִים יֹאמ ְ רוּ כֵּן עַל חֶשְׁבּוֹן, "Regarding this, the poets would say: Come to Cheshbon...." Sichon, the king of Emori, conquered the city of Cheshbon from Moav. Sichon thought he had conquered Cheshbon due to his strength. Sichon was a mighty warrior, and he thought that his strength enabled him to win Cheshbon. Bilaam said that Cheshbon (the city of Moav) was conquered because he cursed Moav. Everyone had his explanation on how the war was won.
חֶשְׁבּוֹן בֹּאוּ, but let us make a true cheshbon, to understand what truly occurred. It wasn't Sichon's strength, and it wasn't Bilaam's curses. It was from Hashem. Rashi explains that Hashem wanted Sichon to conquer Cheshbon and take it away from Moav. This is because the Jewish nation isn’t permitted to conquer any lands from Moav, as it states (Devarim 2:9) אֶת תָּצַר אַל מ ִלְחָמָה בָּם תִּת ְגָּר וְאַל מוֹאָב, "You shall not distress Moav, and you shall not provoke war with them..." Therefore, Hashem enabled Sichon, the king of Emori, to conquer Cheshbon from Moav. After it was conquered, Cheshbon didn't belong to Moav, and the Jewish nation was able to conquer it. So, the war was won by Hashem, and we must remember that.
It states in Shulchan Aruch (Orach Chaim 219:1) ...מ ִדְבָּרוֹת וְהוֹלְכֵי ...ה ַיָּם יוֹרְדֵי ,לְהוֹדוֹת צְרִיכִים א ַרְבָּעָה,הָא ֲסוּרִים בְּב ֵית חָבוּשׁ שֶׁה ָיָה וּמִי ...וְנִתְרַפ ֵּא חוֹלֶה שֶׁה ָיָה וּמִי .וְיָצָא "Four [categories of people] must praise Hashem: those who travelled by sea, those who traversed a desert, those who were ill and became well, and those freed from jail."
לְהוֹדוֹת צְרִיכִים א ַרְבָּעָה, "Four must praise Hashem" is an unusual expression. The word צְרִיכִים, 'must', isn't common in Shulchan Aruch and in halachah. A more common expression would be לְהוֹדוֹת חייבין א ַרְבָּעָה, "Four are obligated to praise Hashem."
Shev Yaakov answers that Shulchan Aruch is telling us that praising Hashem for the salvations is so important, we must do so, even if it wouldn't be an obligation. This is because Chazal tell us that when a miracle happens to a person, he loses some of his merits. His mitzvos become like currency, spent in exchange for the miracle that occurred. However, when he praises Hashem for the miracles that happened to him, he doesn't have to pay for the miracle with his mitzvos.
Therefore, if a miracle happens to a person, לְהוֹדוֹת צְרִיכִים, he must praise Hashem. He must do so, even if it weren’t an obligation. It is for his own good so that he won't lose his mitzvos.
