A dog licking a vessel: Abu Hanifah said washing it once suffices

Zayd Abu Ayyash said: I asked Sayyiduna Sa'd (may Allah be pleased with him) about exchanging barley for sorghum, and he disliked it. Sayyiduna Sa'd said: the Prophet (peace and blessings be upon him) was asked about exchanging fresh dates for dried dates, and he said: "Do dates become less (lighter) when they dry?" We said: Yes. So he forbade it.

It is reported from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that he used to dislike exchanging fresh dates for dried dates, and he would say: These (fresh dates) come to less in the measure or in the qafiz.

It is narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both) that the Prophet (peace and blessings be upon him) forbade selling grapes for raisins by measure.

It is reported from Sa'id bin al-Musayyib that he used to dislike taking fresh dates for dried dates, equal for equal, and he would say: Fresh dates are swollen while dried dates are shrunken. It is mentioned that the view of (Imam) Abu Hanifah is: There is no harm in it.