What is the authenticity of the report

The Shaykh : Here is a question. The questioner says: In the name of Allah, the Most Gracious, the Most Merciful. Al-Shafi'i, Ahmad, Abu Ubayd, al-Daraqutni, al-Bayhaqi, and 'Abd al-Razzaq narrated from Abu 'Amr ibn Sammak, from his father, who said: "I used to sell leather and water skins. 'Umar ibn al-Khattab passed by me and said to me: Pay the charity of your wealth. I said: O Commander of the Faithful, it is only in the leather. He said: Appraise it, then pay its charity."
The question is one: Is this report authentic? And if it is authentic, what is the jurisprudence derived from it?
The answer to this question is that this report is not authentic in its chain of narration. Its defect lies with the narrator of this report from 'Umar directly, and from his son, the narrator from him, who is Abu 'Amr ibn Sammak. Both the son and the father are unknown; they are not known for trustworthiness, memorization, or precision. Therefore, this report is not established from 'Umar (may Allah be pleased with him). Without a doubt, if it were established, it would point to what many, indeed most, scholars hold regarding the obligation of zakah on trade goods, and that they must be appraised and zakah paid from them at two and a half percent, as is well known in the zakah of the two types of currency. However, since that is not established from 'Umar, it is not permissible to derive a legal ruling from it, especially since Imam Ahmad narrated in his Musnad, with a chain better than this one, something that contradicts this report. Imam Ahmad narrated that a group of merchants brought horses from Sham to Madinah, then asked 'Umar (may Allah be pleased with him) to take their charity. 'Umar said: ; meaning by them the Messenger (peace and blessings be upon him) and Abu Bakr al-Siddiq. He explicitly states that the Prophet (peace be upon him) and after him Abu Bakr al-Siddiq did not take zakah on trade goods of this type, which are horses. Since the people at that time were not like the people of our day, the people at that time would press the Muslim rulers to take zakah from them, whereas people today devise schemes to evade the rulings of the Shari'ah to get rid of zakah, which is called "legal stratagems." These merchants pressed 'Umar ibn al-Khattab to take zakah from them on those horses, and 'Umar insisted on his previous position. Then 'Ali ibn Abi Talib (may Allah be pleased with him) intervened in the matter and said: Take it from them, O Commander of the Faithful, and it is a charity among charities, meaning it is not an obligatory zakah. So he took it from them, and their hearts were pleased. This hadith indicates the opposite of what 'Umar's report indicated, namely that zakah is not obligatory on trade goods. From here, we can understand part of the answer to the second question.