Assalaamu alaykum, I have read a hadith in Fortress of the Muslim that says that whoever recites "Hasbiyallaahu Laa Ilaaha Illaa Huwa ‘Alayhi Tawakkaltu Wa Huwa Rabbul-‘Arshil ‘Atheem" seven times will be given what he desires in this world and in the next. I would like to know the authenticity of this hadith please. May Allaah bless you.

All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger. 

Abu Daawood narrated in his Sunan that Abu Ad-Dardaa’ said, “If anyone says seven times in the morning and evening, 'Hasbiyallaahu Laa Ilaaha Illaa Huwa ‘Alayhi Tawakkaltu Wa Huwa Rabbul-‘Arshil ‘Atheem,' Allaah will remove anything that grieves him, whether he is truthful or untruthful in saying it.”

Al-Arnaa’oot in his verification of Sunan Abu Daawood, stated that the reporters of this hadeeth are trustworthy, classified it as a Mawqoof report (i.e. stopped at the level of the Companion), and underlined that the text has an addition that is Munkar (questionable).

It is also cited in ‘Amaal Al-Yawm wal-Laylah by Ibn As-Sunni as a Marfoo' hadeeth (directly attributed to the Prophet, sallallaahu ‘alayhi wa sallam) without that addition. An-Nawawi cited it as well in his book Al-Athkaar and did not classify it as weak.

Shaykh ‘Abd Al-Muhsin Al-‘Abbaad commented on the hadeeth, saying:

“It is a report narrated on the authority of Abu Ad-Dardaa' (his own statement) and an honorable Companion like him would never say such a statement based on his personal opinion. Specifying the reward for this precise number, which is seven times, cannot be expressed on the basis of personal opinion. However, the authenticity of the last sentence of the report - 'whether he is truthful or untruthful in saying it' - is questionable. Earning such a reward is only attainable through truthfulness while reciting the Thikr, hoping for the rewards of Allaah. As for the one who recites this Thikr insincerely and untruthfully (and gets rewarded), this is problematic. Some scholars, though, interpreted untruthful to mean the person who recites the Thikr with an inattentive heart (i.e. he is not mindful of it while he says it). But the authenticity of the wording is definitely questionable.” [Sharh Sunan Abu Daawood]

Allaah knows best.