Allah Ta'aalaa says:
"They have not been commanded, but to render Ibaadat unto Allah sincerely establishing the Deen for Him and turning away from all others."
Rasoolullah sallallahu alayhi wasallam said:
"Verily, Allah does not look at your external forms and your wealth, but He looks at your intentions and actions."
Ikhlaas means to have the intention of only Allah in one's acts of obedience. The motive must be only the Proximity and Pleasure of Allah. This motive must not be contaminated with personal motives of gain or the pleasure of others.
Elimination of riyaa (show) is precisely the acquisition of Ikhlaas.
No matter what type of righteousness an act may be and no matter how little it may be, if it is accompanied by Ikhlaas, it will be permeated with barkat even if there is no helper. Thawaab will increase in proportion to the degree of Ikhlaas. For this very reason it comes in the Hadith:
"A half a mud (a measure) of corn given in charity by my As’haab is nobler than gold equal to Mount Uhad given in charity by others."
The secret is the degree of Ikhlaas. The Ikhlaas in the Sahaabah is far superior to the Ikhlaas in others. Their reward is in terms of their sincerity and love.
The highest stage of Ikhlaas is the rendering of an act for the sake of only Allah Ta'aalaa, creation having absolutely no connection in one's motive. A lesser degree of Ikhlaas is that the act is rendered to please people but it was not motivated by any desire for worldly gain. The motive was merely to please others. The third degree of Ikhlaas is to render an act without having any motive. The motive is neither the Deen not the world. This too is Ikhlaas, i.e. the non-existence of riyaa (show)r