عن أبي هريرة رضي الله عنه مرفوعًا: "المؤمن القوي، خيرٌ وأحب إلى الله من المؤمن الضعيف، وفي كلٍّ خيرٌ، احْرِصْ على ما ينفعك، واسْتَعِنْ بالله ولا تَعْجِزْ، وإن أصابك شيء، فلا تقل لو أني فعلت كان كذا وكذا، ولكن قل قَدَرُ الله وما شاء فعل، فإن لو تفتح عمل الشيطان". [صحيح] - [رواه مسلم] المزيــد ...
Abu Hurayrah (may Allah be pleased with him) reported that the Messenger of Allah (may Allah's peace and blessings be upon him) said: "A strong believer is better and dearer to Allah than a weak believer, and there is good in both. Adhere to whatever brings you benefit, seek the help of Allah, and do not feel helpless. If something befalls you, do not say: 'Had I done such-and-such, it would be such-and-such.' Indeed,'if' opens the way before the devil to act." Sahih/Authentic. - [Muslim]
A believer who has strong faith, not one with a strong body, is what is meant in the Hadīth. Such a believer is better than a weak believer, and dearer to Allah than him. If they are both equal in faith, then indeed the benefit of the strong one extends to others, while the benefit of the weak one is restricted to himself. Thus, a strong believer is deemed better than the weak one, even though there is good in both of them. This is to block the way before people who think that a weak believer is devoid of any good. Undoubtedly, he is better than a disbeliever anyway. Then, the Prophet (may Allah's peace and blessings be upon him) communicates a comprehensive, precise piece of advice, as he commands the Muslims to be diligent in pursuing and achieving what brings benefit to them, whether in terms of religion or worldly affairs. If there is a conflict between a worldly benefit and that related to religion, the latter should be given priority over the former. This is because when one’s religion is good, his worldly affairs will be good as well. Meanwhile, worldly affairs do not maintain their good state if one’s religion is corrupt. He also orders the Muslims to seek Allah’s help even in simple matters and to never yield to laziness and disability.
Having complied with the prophetic advice of diligently seeking benefit, asking Allah for help, and continuing to do the deeds without laziness or submission to disability, he warns them, if they do not achieve the hoped for objective, about saying:"Had we done such-and-such, it would be such-and-such," since this is something beyond their will. A person should do what he is commanded to do, and Allah has full control over His affairs.
As for ‘if’, it opens the way before satanic whispers, grief, regret, and concerns. Therefore, a person should stick to the instructions mentioned in the Hadīth. That is, he should acknowledge that things proceed according to the destination and decree of Allah, the Exalted, Who does whatever He wills.