El-Ah is interpreted in six ways:
1. By el-Ah, a full sibling (sharing both parents), or a maternal sibling, or a paternal sibling is meant; as in the following verses:
His soul encouraged him {that is, the son of Adam}, to kill his brother {that is, his full brother}. (al-Māʾida 5:30)
...I was unable to bury my brother's {that is, my full brother's} corpse. (al-Māʾida 5:31)
If he has a brother or a sister... (al-Nisāʾ 4:12) And similar commands.
2. By el-Ah, what is meant is not full, paternal, or maternal siblinghood, nor brotherhood in religion, but brotherhood in lineage (nasab), that is, tribal kinship; as in the following verses:
And to ʿĀd [We sent] their brother {that is, their tribesman} Hūd. (Hūd 11:50)
Hūd was neither their brother in religion, nor a full, paternal, or maternal brother; but in terms of lineage/ancestry, he was their brother: a tribesman.
And to Madyan [We sent] their brother (that is, their tribesman) Shuʿayb. (al-Aʿrāf 7:85; Hūd 11:84; al-ʿAnkabūt 29:36)
Shuʿayb was neither their brother in religion, nor a full, paternal, or maternal brother; but in terms of lineage/ancestry, he was their brother.
A similar example is found in Sūrat al-Shuʿarāʾ.
3. By el-Ah, brotherhood in religion and in the sense of wilāya (alliance/loyalty) in shirk (associating partners with God) is intended; as in the following verses:
Their brothers (that is, in religion and in the matter of wilāya in kufr [disbelief], the devils are the brothers of the disbelievers) lead them into error. (al-Aʿrāf 7:202)
Indeed, the wasteful are brothers of the devils (that is, in religion and in the matter of wilāya). (al-Isrāʾ 17:27)
4. By el-Ah, brotherhood in the religion of Islam and in the matter of wilāya is intended; as in the following verse:
The believers are but brothers (that is, in the religion of Islam and in the matter of wilāya, only the believers are brothers). (al-Ḥujurāt 49:10)
5. By el-Ah, friend is meant; as in the following verses:
This is my brother (that is, my friend). He has ninety-nine sheep. (Ṣād 38:23)
Would one of you like to eat the flesh of his dead brother (that is, his friend)? (al-Ḥujurāt 49:12)
6. By the word el-Ah, brotherhood in love and affection is intended; as in the following verse:
They will be on thrones, facing each other as brothers {that is, as brothers by virtue of the love and affection they have for one another}. (al-Ḥijr 15:47)