The words in the report of ‘Ali (may Allaah be pleased with him), “Talk to the people” means when preaching and otherwise. “What they appreciate and accept” means, what they may understand, so that they will not be confused.
Hence it was narrated that Ibn Mas’ood (may Allaah be pleased with him) said: “You will never tell a people anything that they do not understand but it will be a cause of confusion for some of them.” Narrated by al-Bukhaari.
Hence it is wise when calling people to Islam not to overwhelm the people with things that they cannot understand, rather one should call them gradually, so that they may gradually comprehend what you are telling them.
The phrase “do you want them to reject Allaah and His Messenger?” means: If you tell the people things that they do not appreciate, do you want them to reject Allaah and His Messenger? Because if you say “Allaah said such and such and His Messenger said such and such,” they will say, This is a lie, if it is beyond their comprehension, and in that case they will not be disbelieving Allaah and His Messenger, rather they will be disbelieving you and the words you attribute to Allaah and His Messenger, thus they will be ultimately disbelieving Allaah and His Messenger, not directly but via the one who told them that.
If it is said: Should we forego speaking of that which people do not understand even though they are in need of that? My answer is: We should not forego that, but we should tell them in a way that is acceptable to them, by telling them gradually, until they accept this idea and feel at ease with it, and we should not ignore that which they cannot understand and say that this is something objectionable so we should not speak of it.
For example: Following the Sunnah which the people are not used to and find objectionable. We should follow it, but after we tell them of it, until their hearts accept it and feel at ease with it.
It may be understood from this report the importance of wisdom in calling people to Allaah, may He be glorified and exalted, and that the daa’iyah must have insight into the mentality of the people he is calling, and use a different approach for each individual.