Shama-il Tirmidhi Chapter 055, Hadith Number A002 (397).

Ibn Seereen says: "The knowledge of hadith (in the same manner all other religious subjects) are included in the deen. Therefore before acquiring knowledge, be aware from whom knowledge is acquired".

Commentary
Ibn Seereen was also an Imaam of his time and is a famous Taabi-ee. He acquired 'ilm from many of the Sahaabah Radiyallahu 'Anhum, and is regarded as the imaam in the art of interpreting dreams. His interpretations of dreams are a hujjah (testimony). The object of his advice is that prior to acquiring knowledge from a person, one should first thoroughly investigate the state of the person's piety, honesty religion and maslak (rule of conduct). One should not follow the sayings of every person, because the following of the sayings of an irreligious person has its effects. This has also been commanded by Sayyidina Rasulullah Sallallahu 'Alayhi Wasallam in a few narrations. This is a general advice as mentioned in athar number one. This athar may also be relevant to the subject of interpreting dreams, as this subject is also important. When a good dream is a portion from the portions of nubuwwah, its importance can be understood. Therefore one should always be careful from whom one is seeking an interpretation of a dream. Is that person capable of interpreting a dream or not. It is for this reason that Imaam Tirmidhi has mentioned this athar here. This advice of Ibn Seereen is not particular or confined to the subject of dreams, but includes all other sciences. The more important the signs are, the more it becomes necessary to seek a competent and knowledgeable person. In our times which is close to the time of qiyaamah, a very dangerous and detrimental element has appeared. That every person, however unlearned or irreligious, after delivering a short inspiring lecture, or writing an article on a aspect of the deen, begins to be considered an 'allaamah or an 'aalim, and by donning coloured clothing begins to be regarded as a sufi, hence people ignorantly begin to follow such a person. In the beginning the general public due to some misunderstanding begin following such a person, and because of their ignorance they are caught in their web. This is because of a general misunderstanding, which has entered the hearts of the public, that 'See what is said and not who has said it'. Although this saying is true, it is for those who understand and differentiate, that which is being said, is it a fact or is it false? Those who cannot differentiate should not follow the sayings of every person they come across, as this will result in a bad and detrimental ending. It is for this reason that in these times, if one claims to be a saint, imaam, or prophet, and Allah forbid, also that of being a God, one group always immediately begins to follow that person. And to Allah is our complaint, and He is the One that grants assistance.