Sūʾ al-ḥifẓ is a weakness in retaining and reproducing reports. A transmitter with deficient memory is not necessarily wrong in every narration; critics assess the pattern and degree of error against more securely preserved routes.
«أَوْ سُوءُ حِفْظِهِ، وَهِيَ عِبَارَةٌ عَمَّنْ يَكُونُ غَلَطُهُ أَقَلَّ مِنْ إِصَابَتِهِ»
Weak retention describes one whose mistakes are fewer than his correct transmissions.
In this terminology, weak retention is distinguished from the more severe excessive error. Independent corroboration may sometimes compensate for such weakness in a particular report, but this must not be generalized to every kind of defect.