With regards to the student of knowledge being gentle in speech, the Shaykh Muhammad ibn Saalih al ‘Uthaymeen rahimahullaah comments:
This is from the most important of the manners of the student of knowledge, regardless of whether he is a taalib– or a matloob, meaning a teacher – then (they should have) gentleness, just as the Prophet sall Allaahu ‘alaihi wa sallam said:
“Indeed Allaah is Rafeeq (gentle), He loves gentleness in all the affairs.”
“Gentleness is not present in a matter except that it beautifies it and it is not taken out from a matter except that it disfigures it.”
However a person must be gentle without being weak. As for being gentle whilst being treated in a humiliating manner and not having his statement accepted and not being taken notice of, then this goes against al hazm (being determined and resolute).
But he should be gentle in the situations (necessitating) gentleness and stern in the situations (necessitating) sternness.
And there is no one more merciful than Allaah, the Mighty and Majestic; but along with that, He says with regards to the male and female fornicator:
Flog each one of them with a hundred lashes. And do not let pity hold you back in their case in (a punishment prescribed) in the Religion of Allaah.
Soorah an Noor (24) aayah 2
So for every situation there is (a correct) saying.
(Sharh hilyah taalib il ‘ilm p50 of Shaykh Muhammad ibn Saalih al ‘Uthaymeen rahimahullaah, translator Nasser ibn Najam)