Praise be to Allah.

Undoubtedly the greatest blessing that Allah bestows upon His slaves is blessing them with guidance to His religion that He has chosen for His slaves and commanded them to follow. Allah, may He be exalted, says (interpretation of the meaning): “This day I have perfected for you your religion and completed My favor upon you and have approved for you Islam as religion” [al-Maa’idah 5:3].

Ibn Katheer (may Allah have mercy on him) said:

This is the greatest blessing that Allah, may He be glorified and exalted, has bestowed upon this ummah, when He, may He be exalted, perfected their religion for them, so they have no need of any other religion or of any prophet other than their Prophet, blessings and peace of Allah be upon him. Hence Allah made him the last of the Prophets, and sent him to humanity and to the jinn. So nothing is permissible except what he permitted, and nothing is forbidden except what he forbade, and there is no religion except what he prescribed. Everything that he has told us is true, and there are no lies in it, as Allah, may He be exalted, tells us (interpretation of the meaning): “And the word of your Lord has been fulfilled in truth and in justice” [al-An‘aam 6:115]. In other words, it is true in what it tells us and it is just in its commands and prohibitions. When Allah perfected the religion for them, He completed His favour upon them. End quote from Tafseer Ibn Katheer (3/26).

Shaykh al-Islam Ibn Taymiyah (may Allah have mercy on him) said:

The greatest blessing that He bestowed upon them was commanding them to believe and guiding them to faith. They are the people of the ultimate blessing that is mentioned in the words (interpretation of the meaning):

“Guide us to the straight path –

The path of those upon whom You have bestowed favor”

[al-Faatihah 1:6-7].

End quote from Jaami‘ al-Masaa’il (4/284).

He also said:

One of the greatest and noblest blessings that Allah has bestowed upon His slaves is that He sent His Messengers to them, and sent down His Books to them, and showed them the straight path. Were it not for that, they would have been like animals and beasts; in fact they would have been worse off than them. So whoever accepts the message of Allah and adheres to it is among the best of creation, and whoever rejects that and rebels against it is one of the worst of creation, and is worse off than dogs, pigs and dumb animals.

End quote from Majmoo‘ al-Fataawa (19/100).

Thus it is clear that the greatest blessing that Allah has bestowed upon His slaves is enabling them to believe in Him and His Messengers, and to adhere to His religion and law. Allah, may He be glorified and exalted, is the Lord of all creation, and He is their Creator and the controller of all their affairs, and He is also forbearing and does not hasten to punish His slave for their wrongdoing or what their hands have wrought, but this blessing is only for those who acknowledge Him, believe in Him and follow His guidance. As for those who disbelieve in Him and disobey him, and are deceived by His forbearance and covering of their sins, so they persist in transgressing against His limits, that will lead to bad consequences for them, and will cause the punishment to be increased for them. Furthermore, even worldly blessings such as provision and well-being, wealth and children, and so on, are only truly a blessing for those who give thanks for them and appreciate them, not for those who are ungrateful for them and use them to disobey Allah.

Shaykh al-Islam Ibn Taymiyah (may Allah have mercy on him) said:

The greatest blessing that Allah has bestowed upon people is faith, which includes both words and deeds, and may increase and decrease; it increases when one does acts of obedience and good deeds, and it decreases when one does evil deeds and commits sins. The more a person increases in doing good deeds, the more his faith will increase. This is the true faith which is mentioned in the words of Allah, may He be exalted, (interpretation of the meaning):

“Guide us to the straight path –

The path of those upon whom You have bestowed favor”

[al-Faatihah 1:6-7].

Are the blessings of this world part of religious blessings or not, and are they truly blessings or not? Concerning that there are two well-known views from the scholars, among our companions and others. The correct view is that they are blessings in one way but are not perfect blessings in every aspect. As for the blessing of religious commitment, in the sense of doing what is enjoined and refraining from what is forbidden, that is all good and it is the true and real blessing according to Ahl as-Sunnah, because in their view it is Allah Who is the Bestower of all goodness. …

End quote from Mukhtasar al-Fataawa al-Masriyyah (268).

Conclusion:

The greatest blessing that Allah bestows upon His slaves is guiding them to know Him and affirm His oneness, follow His Messengers and adhere to His laws. As for worldly blessings, they may be a blessing for those who use them appropriately, and use them to help them obey their Lord.

And Allah knows best.