All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
There is no doubt that the principle in Da'wah (calling people to Allaah) and teaching Islam to others is to be gentle and kind. However, in some circumstances one may drift from this principle, and Abu Hurayrah is one of the best companions of the Prophet and one of the most knowledgeable scholars amongst them.
He was undoubtedly a wise person, and wisdom is to put something in its proper place. Hence, it is not wise to act with softness in a circumstance which requires some harshness, and it is not wise to act with harshness in a circumstance which requires some kindness and gentleness. The scholar acts differently with the questioners according to their different circumstances and the kind of questions they ask.
Indeed, some questioners ask questions argumentively to make things difficult for the scholars, while others ask only to mock the person asked, both of which are forbidden, as Allaah Says (what means): {O you who have believed, do not ask about things which, if they are shown to you, will distress you.}[Quran 5:101]
The scholars stated that the fact that Allaah is not created is something which does not require evidence, as His Existence is an absolute fact and asking about it is useless.
Therefore, a scholar may need to deter the questioner in order to draw his attention that he should not ask such questions. Consequently, the questioner accepts such deterrence because of knowing the status of the scholar on one hand, and knowing that this scholar is keen to achieve his benefit [questioner's benefit] on the other hand.