It is Mustahab (recommended) to give Sadaqah (Charity) of gold, silver or money, which is approximately equal to weight of the hairs shaved off from a newborn baby. Usually the weight of hairs on a newborn’s head is equal to one Dirham, which is equivalent to 3.0618 grams of today.
It should be clear that this order is Mustahab (recommended), which means an action which was done by Prophet (Peace Be Upon Him) ﷺ or his Sahaba (companions) or was liked by them, or was liked by Tabi’een (followers of the companions), but the action was not done always, rather, sometimes it was done and sometimes left. Doing so is rewarded and not doing the same is not a sin.