Ibn Majah

1؎: Ghuluww: To excessively exaggerate something or to be overly strict in it is called ghuluww. For example, the command is to throw pebbles (during the ritual of stoning), and small pebbles suffice. Now, ghuluww would be to throw large stones or rocks and to consider this a more virtuous act. In every matter of religion, engaging in ghuluww is prohibited, and it is a sign of foolishness. It is also ghuluww, for instance, that if someone abandons a recommended (mustahabb) or Sunnah act, one reproaches or abuses him. If someone abandons a Sunnah, it is sufficient to gently relate to him the hadith. If people abandon an obligatory act (fard), then one should command it with firmness. However, in this era, the situation has become such that no one reproaches those who abandon obligations; people maintain friendships with those who neglect prayer, drink alcohol, and consume usury, but if someone does not kiss his thumbs during the adhan or does not stand during the mawlid, they become his enemies. This too is an extreme form of ghuluww, and it is because of such matters that Muslims have been ruined, and just as the Prophet (sallallahu alayhi wa sallam) had said, so it has come to pass.