How sound is the statement reported from Umar that whoever misses the Friday sermon must pray four rak'ahs?

One must strive to attend the Friday prayer upon hearing its adhan, and it is not permissible to miss it without a valid excuse. Whoever catches one rak'ah of the Friday prayer has caught it, and he must add another rak'ah to complete the prayer as two rak'ahs. However, whoever does not catch a rak'ah with the Imam must pray four rak'ahs as Dhuhr. This is the view of the majority of scholars, and it is supported by the Prophet's (peace be upon him) hadith: "Whoever catches one rak'ah of a prayer has caught it." As for what was narrated from 'Umar (may Allah be pleased with him) that whoever misses the sermon should pray four (rak'ahs), its chain of narration is not sound.