1745/1 - Hudhayfah ibn al-Yamān (may Allah be pleased with him) reported that the Prophet (may Allah’s peace and blessings be upon him) said: “Do not say: What Allah wills and so-and-so wills; rather say: What Allah wills and then so-and-so wills.” [Narrated by Abu Dāwūd with an authentic Isnād]
1) The Shariah prohibits anything that leads to associating partners with Allah Almighty. One of such things is saying: What Allah wills and so-and-so wills. This phrase does actually equate between the Creator and the creature, which is the core of polytheism. {Yet those who disbelieve set up equals to their Lord.}
2) When the Shariah prohibits anything, it leads people to what is better and more useful for them in terms of their worldly and religious affairs. So, when a preacher tells people about what is not permissible, he is also recommended to inform them of what is permissible. This makes them more willing to accept the Shariah rulings.
Some people use the need for an alternative as an argument against all those who command what is good and forbid what is evil, refusing to comply unless there is an alternative!
This contradicts the duty of servitude to Allah Almighty and submission to His judgments. When he hears a command by his Lord or the Prophet, a Muslim should say: We hear and we obey.
{As for the believers, when they are called to Allah and His Messenger so that he may judge between them, they say, “We listen and obey.” It is they who are the successful.}