If he wipes only his forelock, without the rest of his head, it does not suffice for him, because Allah the Exalted says: “And wipe your heads” [al-Ma'idah 5:6]. He did not say, “part of your heads.” In the Arabic language, the preposition ba' never conveys the meaning of partiality.
Ibn Burhan said: “Whoever claims that the preposition ba' conveys partiality in the Arabic language has erred” (1). As for the report of al-Mughirah ibn Shu'bah that the Prophet, peace and blessings be upon him, wiped over his forelock, his turban, and his leather socks (2), the validity of wiping the forelock in this case is due to his having wiped over the turban along with it. Thus, it does not indicate that wiping only the forelock is permissible.
The ears are included in it...
His statement, “The ears are included in it,” means that they are included in the head. The evidence is the Prophet’s consistent practice of wiping the ears.
As for the hadith, “The ears are part of the head” (3), many scholars, such as Ibn al-Salah and others, declared it weak. They said that its chains are feeble, and that, because of the extent of their weakness, it does not rise to the level of hasan.