How do we achieve sincerity?

Question:
He says: You mentioned, may Allah preserve you, that the reason for the spread of the call of Shaykh Muhammad ibn 'Abd al-Wahhab and the benefit derived from it was his sincerity. He says: How do we obtain this sincerity? And how do we know that we have achieved it so that we may attain the result?

Answer:
This is something that Allah places in you. If sincerity and a good intention appear in you, that is the objective. Look at your intention: is it an intention for the sake of Allah, or an intention to seek wealth, praise, or something else? Your intention is... they say your intention is... your intention is correct. Look at your intention to call people to Allah: do you want praise and eulogy, or do you want a job? If so, you have no share in the Hereafter. If you want the Face of Allah, and you want sincerity for Allah, and you want to free the servants from shirk (associating partners with Allah), then you are upon good. Yes.