Tafsir of Al-Inshirah 94:5

The fa in His saying, the Mighty and Majestic, "For indeed, with hardship [there is] ease," is—according to what is in al-Kashshaf—eloquent (fasihah). The discourse is a promise made to him, may Allah the Exalted bless him and grant him peace, framed for the purpose of consolation and relief. It is said that the polytheists used to taunt the Messenger of Allah, may Allah the Exalted bless him and grant him peace, and the believers regarding their poverty and hardship, until it crossed his noble mind, upon him be blessings and peace, that they had turned away from Islam because of its people's poverty and their being held in contempt.

So, He, glory be to Him, reminded him of the magnificent blessings He had bestowed upon him, then said—exalted is His affair—"For indeed, with hardship [there is] ease." It is as if He, glory be to Him, said: "We have granted you what We have granted you, so do not despair of the bounty of Allah the Exalted, for with the hardship you are experiencing, there is ease." It is evident here that the al (definite article) in al-‘usr (the hardship) is for ‘ahd (specific reference). As for the tanwin in yusran (ease), it is for magnification (tafkhim); as if it were said, "For indeed, with the hardship, there is a great ease—what an ease!" The intent by it is the conquests that were made easy for them during the days of the Messenger of Allah, may Allah the Exalted bless him and grant him peace, or the ease of the world in absolute terms.