indeed it is the key to blame.
The second state is to contemplate the decree itself and realise that, had the matter truly been ordained for him, it would never have missed him and no one could have withheld it from him.
Accordingly, the Prophet ﷺ guided the servant to what benefits him both when he attains his goal and when he loses it. He forbade him to say “if,” informing him that this word opens the door to Satan’s work because it embodies regret for what has passed, grief, sorrow, and censure of the divine decree; a person thereby falls into sin, and this is from Satan’s handiwork. The prohibition is not for the mere utterance of the word “if,” but for what accompanies it in the heart—feelings that undermine perfect faith and give Satan a foothold.
Should it be said, “The Messenger of Allah ﷺ himself used this word when he ordered his Companions to change their pilgrimage into an ‘umrah while he did not do so because he had brought the sacrificial animals,” the answer is that his statement, “Had I known before what I know now, I would not have driven the sacrificial animals,” speaks of a future course of action and contains no objection to the decree. He was only informing his Companions that if he were to begin the rites anew he would not bring the animals and would enter iḥrām for ‘umrah instead. He said this to encourage them and put their hearts at ease when he saw their hesitation. Therefore, this is not included in the prohibition; it is merely a report of what he would do in the future were the circumstance to arise, and there is no disagreement over the permissibility of that. The prohibition applies only when the word is used in opposition to the divine decree. Allah knows best.
This hadith narrated by Abu Hurayrah is indispensable for every servant. It contains affirmation of the divine decree, affirmation of human acquisition (kasb), and instruction in true servitude to Allah.
Shaykh al-Islām Ibn Taymiyyah, may Allah have mercy on him, summarised its meaning by saying: “Do not fall short regarding what you are commanded, and do not be dismayed by what has been decreed.”