Shaikh Shaddad bin Hakim (Allah have mercy on him) used to say:
“Whoever possesses the following three characteristics should instruct people; if not, then he should leave off teaching.
1. He reminds people of God’s favors in order that they give thanks for them;
2. He reminds them of their sins in order that they repent from them; and
3. He reminds them of their enemies (nafs & Shaytan) in order that they beware of them.”
Ikhlaq as-Saliheen, translation Tambih al Mughtarin of of Imam Sha’rani (Allah have mercy on him)