It has been stated in definition of Ikhlaas,
"Ikhlaas is when the servants internal and external actions are the same (i.e. are in agreement with each other).
And Riyaa is when the external actions are better than the internal actions (of the heart).
And truthfulness in one's sincerity is when the internal is better (developed) than the external.
(Refer to Madaarij us-Saalikeen for this definition 2/91).
Bilaal bin Sa'd (rahimahullaah) said,
"Do not be a wali (friend) of Allaah outwardly, yet an enemy to him internally"
(Ahmad in az-Zuhd, Abu Nu'aym in al-Hilyah).
It has been stated,
"Ikhlaas is that you do not request anyone to witness your action except Allaah, and that you do not seek anyone to reward you (for it) except Him".
Salamah bin Dinar said,
"Hide your good deeds (from the people) just like you hide your evil deeds".
(Abu Nu'aym, Bayhaqee)
And in a narration in al-Bayhaqee,
"Hide your good deed like you hide your evil deed, and do not be amazed with your own action, for you do not know whether you are happy or wretched (in the Hereafter)"