Explanation of the words of Imam al-Nawawi (may Allah have mercy on him) regarding what he quoted: "

The Shaykh : In the name of Allah, the Most Gracious, the Most Merciful.
The author (may Allah have mercy on him) said, in what he quoted from Abu Hurayrah (may Allah be pleased with him), that the Messenger of Allah (peace and blessings be upon him) said on the day of Khaybar And in another wording on the day of Khaybar, meaning the day of the Battle of Khaybar. Khaybar was a group of fortresses and farms that belonged to the Jews, located about a hundred miles northwest of Madinah. The Prophet (may Allah’s prayer and peace be upon him) conquered it, as is well known in the biographies. The Jews were working in it, so the Prophet (may Allah’s prayer and peace be upon him) made a treaty with them to remain there as farmers, with half the produce belonging to them and half to the Muslims. They remained on that basis until ‘Umar ibn al-Khattab (may Allah be pleased with him) expelled them during his caliphate, expelling them to Sham and Azraq. The Prophet (may Allah’s prayer and peace be upon him) said: The banner is what we call the flag, which the commander carries so that the army behind him can follow it. He said: a man, an indefinite noun, so it is not known who he is. ‘Umar ibn al-Khattab said: “I did not desire leadership except on that day”, hoping that he would be the one the Prophet (may Allah’s prayer and peace be upon him) mentioned. So he longed for it, and the people spent that night discussing and speculating, each one hoping to be given it. When morning came, the Prophet (peace and blessings be upon him) said: his cousin. They said: meaning he had pain in his eyes. immediately. And Allah is Able over all things. So he did (may Allah be pleased with him). When he had walked a little, he stopped, but he did not turn back because the Prophet (peace and blessings be upon him) had told him not to turn back. So he shouted at the top of his voice: without turning back, because the Messenger (may Allah’s prayer and peace be upon him) had said not to turn back, so he did not turn back. He said: This word is a great word; if the heavens and the earth were weighed against it, it would outweigh the heavens and the earth. This word is the means by which a person enters from disbelief into Islam; it is the gate of Islam: the testimony that there is no god but Allah and that Muhammad is the Messenger of Allah. Because “There is no god but Allah” is not merely a phrase that a person says with his tongue, but it has conditions and matters that must be fulfilled. For this reason, it was said to some of the Salaf that the Prophet (peace and blessings be upon him) said: He said: Yes, it is the key to Paradise, “There is no god but Allah,” but it must be accompanied by action, because a key needs teeth. May Allah have mercy on him. A key needs teeth; if you came with a key without teeth, it would not open. So the saying of the Messenger (may Allah’s prayer and peace be upon him): includes everything by which a person becomes a disbeliever along with saying “There is no god but Allah.” So if a person disbelieves, even if he says “There is no god but Allah, Muhammad is the Messenger of Allah,” but he commits an act of disbelief, then this word does not benefit him.
For this reason, the hypocrites used to mention Allah, saying “There is no god but Allah” Their appearance and form were as if they were the most perfect of the believers in faith. And they would come to the Messenger (peace and blessings be upon him) and say to him: The speech is emphatic. “We testify that you are indeed the Messenger of Allah.” “We testify,” “that,” and “indeed” are three emphatic markers. “We testify that you are indeed the Messenger of Allah.” So the Lord of Majesty and Honor, who knows what is in the breasts, said: He gave them a testimony with a testimony that the hypocrites are liars. Three emphatic markers. Allah (Mighty and Majestic) confirmed the lie of these people by their saying: “We testify that you are indeed the Messenger of Allah” with three emphatic markers. So not everyone who says “There is no god but Allah” is protected in his blood and his wealth, because the Prophet (peace and blessings be upon him) made an exception, saying:
And when those who withheld zakah, from among the Arabs, withheld it after the death of the Prophet (peace and blessings be upon him), and Abu Bakr (may Allah be pleased with him) prepared to fight them, some of the Companions spoke to him and said: How will you fight them when they say “There is no god but Allah”? He said (may Allah be pleased with him): “By Allah, I will surely fight those who separate between prayer and zakah” Zakah is the right of wealth, and the Prophet (peace and blessings be upon him) said: So he fought them (may Allah be pleased with him) and succeeded, and praise be to Allah.
So the conclusion is that not everyone who says “There is no god but Allah” is protected in his blood and his wealth, but the rights must be fulfilled. For this reason, the scholars (may Allah have mercy on them) said: If a village from among the villages left off the adhan and the iqamah, they do not become disbelievers, but they are to be fought, and their blood is made lawful until they call the adhan and the iqamah, even though the adhan and the iqamah are not among the pillars of Islam, but they are among the rights of Islam. They said: And if they left off the prayer of the festival, for example, even though the prayer of the festival is not among the five obligatory prayers, if they left off the prayer of the festival, it is obligatory to fight them. They are to be fought with swords and bullets until they pray the festival, even though the prayer of the festival is a collective obligation, or a recommended practice according to some scholars, or an individual obligation according to the stronger opinion. But the point is that fighting may be permissible even with the Islam of those being fought. It may be permissible even with the Islam of those being fought, so that they submit to the apparent manifestations of Islam. For this reason, he said here:
And in this hadith is evidence that it is permissible for a person to say: “I will surely do such and such” in the future, even if he does not say “if Allah wills.” But we must know the difference between a person who reports what is in his heart and a person who reports that he will do it, meaning he intends the action.