There is no guarantee that all the people won’t become corrupt except a party from the people of Sham (Syria, palestine, jordan) and deserting the people of truth will not harm them.

Trimidhi narrated from Thawban that the Messenger of Allah(ﷺ) said:

“I only fear for my Ummah from the misguiding A’immah.” He said that the Messenger of Allah (ﷺ) said: “There will never cease to be a group from my Ummah manifest upon the truth, they will not be harmed by those who forsake them until Allah’s Decree comes.”Trimidhi said Hasan Sahih.

Muslim narrates from
Uqba b.Amir the Prophet said :

“There will always be a group in my Umma that will fight according to the order of Allah, victorious over their enemies and there will be no harm on them from their detractors until the hour comes and they will be triumphant.”

Muslim also narrates via Mu`awiya who said: I heard the Messenger of Allah say: “There will always be a party from my Umma that will be steadfast on the order of Allah; they will not be harmed by those who oppose them or abandon them, until the order of Allah comes and they will be triumphant over humankind”.

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Muslim narrated From Jabir b. Samura that the Prophet (ﷺ) said:

This religion will continue to exist, and a group of people from the Muslims will continue to fight for its protection until the Hour is established.

Similar was narrated from al-Mughira b. Shuba, from Jabir ibnAbd Allah, from Abu Dawud form `Imran bin husayn, Uqbah ibn al Husayn etc. Ibn taymiyyah said the hadith is Mutawattir.

Muslim narrated from Sa’d b. Abu Waqqas that the Messenger of Allah (ﷺ) said:

The people of the West will continue to triumphantly follow the truth until the Hour is established.

Imam Ahmad said the people of west are the people of Ash Sham.

The Messenger of Allah (blessings and peace of Allah be upon him) said: “If the people of ash-Shaam become corrupt, then there is no goodness in you, but a group of my ummah will remain victorious, not harmed by those who let them down, until the Hour begins.”

Authenticated by At-Tirmidh.

Ibn Taymiyah said:

The Prophet (blessings and peace of Allah be upon him) highlighted the distinct character of the people of ash-Shaam by noting that they will continue to comply with the commands of Allah until the end of time, and that the victorious group will remain among them until the end of time. This is speaking of an ongoing matter that will remain with them, that they will be numerous and strong.

This description does not apply to anyone in the Muslim world except the people of ash-Shaam… knowledge and faith are still present in that land, and whoever fights in that land to support the faith will be victorious and will be granted divine help.

Majmoo‘ al-Fataawa (4/449).