In the Name of Allaah, the Entirely Merciful, the Especially Merciful.
Sincerity is the reality of this Deen (Religion) and the key in the possession of all those that call on to the Path of Allaah and aspire to earn the Ultimate reward of a good life in this world, a resting place in the grave and a favorable decision on the Day of Judgement.
The Messenger of Allaah (Pbuh) said: "Whoever acquires knowledge by which the pleasure of Allaah is sought, but he only acquires it for the purpose of worldly gain, will not smell the fragrance of Paradise on the Day of Resurrection. (Hasan)
With Ikhlas (sincerity) a man seeks the pleasure of Allaah even with little deeds while with Riya' (show off) a man earns the wrath of Allah even with many deeds.
Dawud ibn Abi Hind fasted for 40 years without his family knowing, he would take his lunch out with him and donate it in the street. Siyar Vol. 6 p378.
Most of us today will tell the world via social media that we are fasting the voluntary fast and here was a salaf who fasted 40 years without his family knowing, a spiritual secret between him and Allaah worthy of complete reward from Allaah.
It is reported that when Ibn Abi Layla prayed[at night], if someone entered [his house], he would lie down on his bed[as if he was sleeping].
Also, the author of "Suwarun min hayaati-t-Tabi'n" wrote that Urwa bin Zubayr read a quarter of the Qur'an from the Mushaf during the day and he will recite a quarter from memory at night. Don't ask me how long he did this....it was narrated that Urwa read conservatively half of the Qur'an daily for more than fifty years of his life.
We are warned against teaching people just to receive praises from them and hankering after titles reserved for sincere scholars.
We are warned against spending on the poor just to be known and celebrated as being generous.
We are warned against fighting for the cause of Allaah just to be known as a mujahid.
Those that hide their righteous deeds as they hide their sinful deeds and seek only for Allaah's pleasure, Allaah has prepared for them what eyes have not seen.
On the Day of Judgement, Allaah will call out on His servants that used to obey Him in seclusion even though they didn't see Him and will be pleased with them.
Uwais al-Qarni conservatively is said to be the best of Tabi'in but he was reported to have said that his greatest aspiration was to live among the people without them knowing him.
May Allaah make us successful through this Deen and may Allaah make this Deen successful through us.