'Ilm al-jarh wa'l-ta'dil is the discipline of examining every narrator in a chain — declaring him reliable (ta'dil) or criticizing his memory or integrity (jarh) — so that only trustworthy transmissions are accepted. Its Quranic root is Allah's command, "If a faasiq (corrupt person) comes to you with news, verify it" (49:6), which the scholars applied by investigating the precision and character of each reporter. This is legitimate, indeed obligatory scrutiny to protect the religion, not forbidden backbiting; it was practiced by the Companions and refined into a rigorous science by imams such as Yahya ibn Ma'in, Ahmad ibn Hanbal, and al-Bukhari.
Evidence — the daleel
On deen2u
Informational, not a personal fatwa. Consult a qualified scholar for rulings on your situation.