أَنْ يَكُونَ قَدْ شَارَكَ الثِّقَاتِ مِنْ أَهْلِ الْعِلْمِ وَالْحِفْظِ فِي بَعْضِ مَا رَوَوْا، وَأَمْعَنَ فِي ذَلِكَ عَلَى الْمُوَافَقَةِ لَهُمْ
Translation: He should first have participated with reliable learned preservers in transmitting some of their reports, showing substantial agreement with them.
“Sharing” concerns verifiable common material, while sustained agreement points beyond a chance coincidence. A well-established pattern of concordance provides evidence of precision that can make a later unique addition more credible.