Do not recommend someone and praise him/[her] except upon knowledge!

Imaam-ul-Barbahaari (rahimahullah) said: "It is not permissible for a muslim male/ [female] to say so-and-so is a person [or] possessor of the sunnah, until you become aware from him/[her] that indeed he/[she] has gathered within himself/ [herself] the attributes of the sunnah, don't say about him/[her], he is a person of the sunnah until he/[she] has gathered within himself/[herself] all of the sunnah." [Point #160 of "Ittihaaf-ul-Qaari bit-T'aleeqaat 'ala Sharh-is-Sunnah"]*

Shaykhuna allaamah Saalih al-Fawzaan [hafithahullah] mentions: [in his commentary on Sharh-us-Sunnah, page 222, volume #2] "Don't recommend a person and praise him/[her] except upon knowledge; So you do not mislead the people by your praise of him/[her] and he/[she] is not like you have said. So if you realize from him/[her] and from his/[her] way and from his/[her] knowledge and from his/[her] uprightness then surely you recommend him/[her]. As for [you] proceeding in praising and recommending him/[her] and you don't know anything about him/[her] than this is a dangerous recommendation [and] you have mislead the people in reference to this person. If only those who recommend people would stop at that [boundary], and not recommend except those who fulfill the conditions of recommendation. [This is] because the recommendation is a certificate [of endorsement]. So when the recommendation is not correct it has become false testimony.
[And] his statement [rahimahullah]: (Indeed he has gathered within himself/[herself] the attributes of the sunnah), the attributes of the sunnah are in [ones] creed and in [ones] knowledge and in [ones] acts/deeds and in following the Righteous Predecessors. As for [in the case] when there is not except one attribute, then do not rule upon him/[her] that verily he/[she] is from Ahlus-Sunnah based on the presence of one attribute or one thing, So how about the one who does not have anything from the attributes of the sunnah?!"
*[The corresponding point number, in the English translation, of the text of Sharh-us-Sunnah is point #158]