Musar zu Dewarim 12:11

They further said in Sifri (Devarim Piska 68): "'and all your choice vows' (Devarim 12:11) - one should bring only from the choicest."

To illustrate, obviously, it is proper for every person to arrive early and run to perform a mitzva, striving to be among those occupied in it. However, sometimes this could lead to a dispute, whereby there will be more desecration of the Name of Heaven and shame to the mitzva than honor. In such cases, certainly the Chasid is obligated to abandon the mitzva and not pursue it.

But there are some additional matters of Piety, which if a person were to do before the common people, they will laugh at him and ridicule him, thereby sinning and incurring punishment through him, and this is something he could have abstained from doing since these things are not complete obligations. Thus, for such things, it is certainly more proper for the Chasid to abstain from it than to do it. This is what scripture says: "and walk discreetly with your G-d" (Michah 6:8). Many great Chasidim abstained from their pious practices when in the presence of the common masses because it appears like arrogance.