How sound is the Hadith: "The best of the people of Iraq will go to Sham, and the worst of the people of Sham will come to Iraq"?

The report referred to is what Ahmad transmitted from Abu Umamah (may Allah be pleased with him), as a statement attributed to him (mawquf), where he said: "The Hour will not be established until the best people of Iraq move to Ash-Sham, and the worst people of Ash-Sham move to Iraq." The chain of transmission for this narration is weak, and it is a statement of Abu Umamah himself, not attributed by him to the Prophet (peace and blessings be upon him).