Imam Hassan Askari (AS) said:

I recommend to you to adopt Divine Piety, devotion to your religion, endeavor in the way of Allah (SWT), telling the truth and give back whatever given to you in trust to its original owner whether he is a good person or not, perform lengthy prostration (Sijdah), and be good neighbours; because the Prophet of Islam (PBUH) has come for these commands. Perform congregational prayers with other tribes and take part in their funeral processions, and visit their ill people, and observe their rights, because when any of you is steadfast in religion, and tells the truth, and is trustworthy, and has good behaviour toward others; others will say: This person is Shia and this makes me happy.

Fear God and do not embarrass us (the Ahlul Bait (AS)). Invite others to us, and prevent any falsehood which is said about us; because whatever good is said about us, we (the Ahlul Bait (AS)) deserve it, and whatever bad is said about us, we are not like that. We have a right in the book of God, and we are relatives of the Prophet (PBUH), and purity given to us by God and no one can claim that except us, and if anyone does so, he is liar. Remember God and death a lot, and recite the Quran and send Salawat to the Prophet (PBUH) a lot, and indeed reciting Salawat has ten rewards. Do not forget my recommendations in my will, I leave you in the protection of Allah (SWT), and send Salam to you [1].

[1] Beharul Anwaar, Vol. 78, Page 371.

Source: en.shafaqna.com