"And those who believed afterwards" means: after the conquest of Mecca and after the emigration had ceased, "and migrated and fought with you, then they are of you."
Yahya [narrated] from Hammad ibn Salamah, from Abu al-Zubayr, from Tawus that Safwan ibn Umayyah, Suhayl ibn Amr, and Ikrimah ibn Abi Jahl arrived in Medina. The Prophet (peace be upon him) said to them: "What has brought you here?" They replied: "We heard that there is no faith for the one who does not emigrate." He said: "Indeed, the emigration has ceased, but there remains struggle (jihad) and good intention." Then he said to Safwan ibn Umayyah: "I adjure you, O Abu Wahb, to return to the valleys of Mecca."
"But those of kindred, some are closer to others in the Book of Allah." Muhammad said: Meaning, in the ordinance of Allah; some commentators have mentioned this.
"Indeed, Allah is All-Knowing of everything."
Sa'id [narrated] from Qatadah that Abu Bakr al-Siddiq said: "This verse with which Allah concluded Surah al-Anfal concerns that which is inherited through kinship from the agnatic relatives ('usbah)."
Muhammad said: "Ulu al-Arham" (those of kindred), the singular form of it is "Dhu" (possessor of), from a different root word.