Third: Among the qualifications necessary for a Da`y is that he should have patience, kindness, and gentleness with forbearing temperament as the prophets (peace be upon them) were.
Never should a Da`y be rushing, violent, or unduly strict. Rather, he has to be patient, forbearing and kind while practicing Da`wah. To this effect, we have stated some evidence earlier. For example, Allah (Glorified and Exalted be He) says:
“Invite (mankind, O Muhammad صلى الله عليه و سلم) to the Way of your Lord (i.e. Islâm) with wisdom (i.e. with the Divine Revelation and the Qur’ân) and fair preaching, and argue with them in a way that is better.” [Surah Al-Nahl, 16: 125]
He (Glorified be He) also says: And by the Mercy of Allâh, you dealt with them gently. In the story of Musa (Moses) and Harun (Aaron), Allah (Glorified and Exalted be He) says:
“And speak to him mildly, perhaps he may accept admonition or fear (Allâh).”[Surah TaHa, 20: 44]
The Prophet (peace be upon him) is authentically reported to have said:
“O Allah, whoever gains control over some affairs of my people and is hard upon them, be hard upon him, and whoever gains control over some affairs of my people and is kind to them, be kind to him.”
[Muslim, Sahih, Book on rulership, no. 1828; and Ahmad ibn Hanbal, Musnad, vol. 6, p. 93.]
So, it is obligatory for you, slaves of Allah, to be kind in your Da`wah, and not to be harsh with people. Do not make people turn away from Islam because of your harshness, ignorance or violent, harmful approach. It is thus obligatory for you to be forbearing, gentle, pleasant and lenient in speech so that your words may have an effect on the heart of your brother, or that it may have an effect on one toward whom your Da`wah is directed. As such, people will receive your Da`wah better, will be affected by it and will show appreciation. On the contrary, harshness causes disaffection, alienation, and division, not unity.
Fatwas of Ibn Baz : Volume 1 > Da`wah to Allah and the manners of those calling to Him > Fourth: Morals and etiquette of the Da`ys to Allah