Title: Kitaabun-Nikaah (The Book of Marriage) from Shaikh Saalih al-Fawzaan’s explanation of Buloogh al-Maraam min Adillatil-Ahkaam of Al-Haafidh Ahmad Ibn `Alee Ibn Hajr al-Asqalaanee (Born 773H, Died 852H). Shaikh Al-Fawzaan’s tremendous explanation is entitled Tas-heel al-Ilmaam bi-fiqhil-Ahaadeeth min Bulooghil-Maraam and is printed in seven volumes. The following is a translation of this important and very enlightening chapter, adapted in places for brevity and simplicity. The following is from volume 4.
Al-Haafidh Ibn Hajr (rahimahullaah) said:
978. Narrated Ibn `Umar (radiyallaahu `anhumaa) said that Allaah’s Messenger (salallaahu `alaihi wassallam) said:
“None of you should ask for a woman’s hand in marriage when his brother has already done so until the one who has already proposed leaves off his desire to marry her, or he gives him permission.”
Agreed upon, and this is the wording of al-Bukhaaree.
[Bukhaaree, no. 5142. Muslim, no. 1412]
Shaikh Saalih al-Fawzaan (hafidhahullaah) said:
This hadeeth contains within it respect and honour for the rights of the Muslims and the forbiddance of transgressing those rights. And from them is: when a man proposes to a woman. Then thereafter it is not permitted for anyone to come along and propose to her until the one who made the first proposition finishes, either because his proposal was accepted or it was not accepted, or if he gives the second proposer permission after he himself decides to step back. This is because of the fact that since he was first to propose, it became his right. So it is not allowed for anyone to transgress that and propose to her after he has proposed to her, because if one was to propose that would be considered as a transgression against the the right of a Muslim. And also because this sows the seeds of animosity and hatred between the Muslims.
So it is forbidden upon a person to propose to a woman who has already been proposed to before him, unless it is clear to him that the first proposer has been rejected or that the first proposer gives him permission; because that was his right first. However, if a second proposer was to come along and propose regardless of the first proposer and then was to marry her, then the majority of the Scholars hold that the marriage contract is sound and valid, even though he is sinful. Some of the Scholars such as the Dhaahiriyyah  hold that such a marriage contract is not valid.
[See Badaa’i` as-Sanaa’i` of al-Kaasaanee 3/479; Bidaayatul-Mujtahid 1/754; al-‘Umm 5/62; al-Insaaf of al-Mardaawayy 8/35.]
And this is just as it is forbidden for a Muslim to outbid his brother once a purchase of a commodity has concluded, or to try and buy what his brother has already bought, or to put in a counter offer against his brother once a price has been agreed.
So these are the rights of the Muslims that it is not permitted for a person to transgress against. And for this reason the Prophet (salallaahu `alaihi wassallam) said, “when his brother has already proposed.” So brotherhood necessitates the forbiddance of transgression between brothers, and that every person respects and honours his brother.
 The Dhaahiriyyah are ascribed to Dawood b. `Alee al-Asbahaanee adh-Dhaahiree (rahimahullaah). They take the fiqh rulings of the Qur’aan and Sunnah more “literally” than the other schools of thought. Other scholars of the Dhaahiriyyah include: Abu Hayyaan al-Anduloosee, Ibn Hazm al-Anduloosee (author of the famous al-Muhalla and Ihkaam al-Ahkaam).