Don’t be fooled by anyone until you know his beliefs

Imam Abu Shama said: “Most often people innovate precisely for this reason: they begin to consider some person as possessing knowledge and fear of God, while he is not. And people begin to look at his words and deeds and follow him, thereby ruining their deeds.”
See “al-Ba’is ‘ala inkar al-bida’ wal-hauadis” 175.

According to Anas ibn Malik (may Allah be pleased with him), it is reported that the Messenger of Allah (peace and blessings of Allah be upon him) said: “ You should not admire anyone until you see what he will die on! Indeed, a person can do good deeds throughout his life, and if he died in such a position, he would enter Paradise, but he changes and begins to do bad deeds. And indeed, the servant of Allah can do bad deeds throughout his life, and if he died in such a position, he would enter Hell, but he changes and begins to do good deeds. And if Allah wants good for His slave, then He begins to use him before he dies“. He was asked: “O Messenger of Allah, how does Allah use him?” The Prophet (peace and blessings of Allaah be upon him) replied: “Guides him to do good deeds, and then takes him along the way.”
“as-Silsila as-sahiha” 1334,

Ibn Mas’ud (may Allah be pleased with him) said: “Do not blindly imitate people in your religion! Indeed, if he believes, you also believe; if he falls into unbelief, you also fall into unbelief. If someone cannot do without imitating someone, then let him do taqlid after the dead, leaving the living, for truly, the living is not protected from temptation.
al-Bayhaqi in “as-Sunan al-kubra” 10/116

Ibn ‘Umar (may Allah be pleased with him) said: “Whoever wants to imitate, let him imitate those who died, and these are the companions of Muhammad (peace and blessings of Allah be upon him)! They were the best members of this community, had the most pious hearts, were the most knowledgeable, and were the furthest from pretense. These were the people that Allah chose to be the companions of His Prophet (peace and blessings of Allah be upon him)! ”
Abu Nu’aym in “al-Hilya” 1/305

Al-Hasan al-Basri said: “Neither fasting, nor prayer, nor Hajj, nor ‘Umrah, nor sadaqah, nor diligence in the path of Allah is accepted by an adherent of innovations.
Ibn Batta in al-Ibana 1/125.

Abu Shama said: “Most often people innovate precisely for this reason: they begin to consider some person as possessing knowledge and fear of God, while he is not. And people begin to look at his words and deeds and follow him, thereby ruining their deeds.”
See “al-Ba’is ‘ala inkar al-bida’ wal-hauadis” 175.

Sheikhul-Islam Ibn Taymiyyah said: “Beware of being seduced by the asceticism of the infidels and adherents of innovations! Indeed, a wicked believer (from among the Sunnis), who longs for both the eternal world and the mortal world, is better than the ascetics from among the adherents of innovations and infidels, either because of the wrongness of the creed of the latter, or because of the wrongness of their aspirations, or for both reasons ” .
See Majmu’ul-fataawa 20/152.