Say what you do? Do what you say?

Today I shared a hadith, something about the 4 things that could guarantee Jannah.
1. Good words
2. Spreading the Salam
3. Maintaining good relationships
4. Praying when others sleep. (qiamullail)

So as I ended the sharing session, i began pondering..have i myself achieved in practicing these things that i say? So do i have the right to speak? To preach? Is it true that one must not say what he is incapable of doing? Should we just only speak of deeds that we have done and never advice others of sins that we are still doing? So as I thought about it the whole night, I came across this hadith..

On the authority of Anas RA; He said that they (the companions) once asked Rasulullah SAW:
" Ya Rasulullah, is it true that we should not preach others to do good, until ourselves have done it,
and that we should not prevent them from certain sins, until ourselves have succeeded in preventing all? "
And in answering, he (Rasulullah) said:
" It's not like that. Preach others of deeds, though you haven't done them and prevent others from sins, though you haven't avoided all of them."
( at-Tabrani - assogheer wal awsot )

If any of you have proof that this hadith is dha'if, please state, because i just read it in a book.