In the name of Allaah, the Most Merciful, the Bestower of Mercy.
Al-Hāfidh Ibn Hajr said:
974-976. Narrated Jaabir (radiyallahu ‘anhu) who said that Allah’s Messenger (salallāhu alaihi wasallam) said:
“When one of you proposes to a woman for marriage, if he is able to look at what will induce him to marry her, he should do so.”
Reported by Ahmad, Abu Dawood, and all the narrators in the chain are trustworthy. Al-Haakim graded it as Saheeh.
The narration also has support with what is narrated by at-Tirmidhi and an-Nasā’i from al-Mugheera 
Also reported by Ibn Maajah and Ibn Hibbaan from the hadeeth of Muhammad Ibn Maslamah.
Shaikh Sālih al-Fawzān said:
This hadeeth proves that is permitted in the Shariah to look at the one proposed to. So if a person intends to marry a woman, and desires to marry her regardless of whether he has already proposed to her or not; then it is recommended that he looks at her – towards that which will induce him and place in him a desire for her, so that he becomes well-acquainted with the one he is about to marry – and so that he is not ignorant concerning her. And as a result of that, there is a distancing from living in an unhappy marriage and in disharmony. So if he sees her, and he is acquainted with her, then this leads to harmony between the two of them, and removes risk, and removes the ignorance concerning her appearance. And for this reason, there occurs in another hadeeth:
“For indeed, that is more suitable so that there is harmony between the two of you.”
Meaning: that by doing so, you will attain harmony and agreement because you took her whilst you knew her. You know her beauty or unsightliness. You know the fullness of her body or its slenderness.
So this is proof that there is no problem in looking at the one being proposed to, rather it is something recommended. However, this looking should be towards her face and hands. This is because the face shows you her beauty, and her hands show you the fullness of her body or its slenderness.
And it suffices that one looks at these places, and not to increase upon that. And this is done in the presence of her Waliyy (father or appointed guardian). Or that he hides from her in a place, and snatches looks at her just as Jābir (radiyallahu ‘anhu) did, as occurs in a narration (see Abu Dawud, no. 2082).
And as for being secluded and alone with her, then that is forbidden, and travelling with her, then that is even worse. It is not permitted for a man to be secluded with a strange woman due to the saying of the Prophet (salallāhu alaihi wasallam):
“There is not a man who is alone with a woman except that Shaytān is the third amongst them.”
Reported by at-Tirmidhi, no. 2165; an-Nasā’i in al-Kubrā, no. 9219.
This hadeeth proves that the origin of the affair is that it is forbidden to look at strange or unrelated women – and that is because the Prophet (salallāhu alaihi wasallam) only made the allowance for the one proposing for marriage. So this proves that the origin is that it is prohibited due to the tribulations and temptations it leads to. Allaah, the Most High, said:
قُل لِّلْمُؤْمِنِينَ يَغُضُّوا مِنْ أَبْصَارِهِمْ وَيَحْفَظُوا فُرُوجَهُمْ ۚ ذَٰلِكَ أَزْكَىٰ لَهُمْ ۗ إِنَّ اللَّهَ خَبِيرٌ بِمَا يَصْنَعُونَ
وَقُل لِّلْمُؤْمِنَاتِ يَغْضُضْنَ مِنْ أَبْصَارِهِنَّ وَيَحْفَظْنَ فُرُوجَهُنَّ
“Tell the believing men to lower their gazes and guard their private parts. That is purer for them. Indeed, Allah is Acquainted with what they do. And tell the believing women to lower their gazes and guard their private parts.” [An-Noor 30-31]
So this is an important matter and a rebuttal of those who say: “The woman is a human being, so why does she have to wear this hijab.” They mock and say: She is like a walking tent; following worn-out and outdated practices; this behaviour is restrictive upon the woman; this code of conduct [in Islaam] is because of evil suspicions [Muslims have] towards women, and other similar statements of disbelief (kufr) – and Allaah’s refuge is sought. And they desire, by making these statements, that the woman should be free to do as she pleases.
Rather, a person does not have the freedom to do as he pleases in matters that have been prohibited by Allaah – or to do that which entails falsehood and Shirk. He does not have the freedom to oppose the Sharee`ah of Allaah, the Mighty and Majestic. For each person is a servant of his Creator, and he is obliged to restrict himself to the Sharee`ah of Allaah, the Most Perfect, the Most High.
A human has been created by Allaah as a slave. So either he is a slave to Allaah, or he is a slave to the Shaytaan. So if he restricts himself to the Sharee`ah of Allaah and His Religion, then he is a slave of Allaah [his Lord and Creator] – and if he exits the Sharee`ah of Allaah and his Religion, and calls to “freedom” to do as one pleases, then he is a slave to the Shaytaan.
Al-‘Allāmah Ibnul-Qayyim (rahimahullah) said: “They fled from the enslavement of the One for Whom they were created. And they became enslaved to the soul and the Shaytān.”
Allaah, the Most High, said:
أَفَرَأَيْتَ مَنِ اتَّخَذَ إِلَٰهَهُ هَوَاهُ
“Have you seen he who has taken as his god his [own] desire.” [Al-Jāthiyah: 23]
So he becomes a slave to his own whims and desires, or enslaved to the Dirham and Deenaar (units of currency), just as the Prophet salallāhu alaihi wasallam) said:
“Wretched indeed is the slave of the Deenaar and the Dirham, and the slave of plush velvet, silk and luxuries. He is pleased only if he is given, and displeased when he not given.” [Bukhāi no. 2886, from Abu Hurairah]
So a person is, without doubt, a slave. So either he is a slave to Allah or, he is slave to someone else. There is no such thing as the freedom to do as one pleases as they claim. Yes, in reality, there is not to found any freedom [in following one’s whims and society].
Rather, the true freedom is that one is a slave to Allah, and he is thus free from the enslavement of Shaytaan, and he is free from the following of whims, and from the following of desires. In this way, a person gains true freedom. If he is a slave to Allaah – he is free from the worship of the Shaytān and free from the worship of whims and desires. So this is true freedom.
 Ahmad, 14585; Abu Dawood, 2082; Al-Hakim, 2/165. The hadeeth is Hasan].
 At-Tirmidhee, 1087; Ibn Majah, 1866; An-Nasaa’ee, 6/69-70. The hadeeth is Saheeh.
 Ibn Maajah, 1864; Ibn Hibban, 1866. The chain of narration is weak.
Adapted from volume 4, Kitābun-Nikāh (The Book of Marriage) from Shaikh Sālih al-Fawzān’s explanation of Bulūgh Al-Marām min Adillatil-Ahkām of Al-Hāfidh Ahmad Ibn ‘Ali Ibn Hajr Al-Asqalāni (born 773H, died 852H), entitled Tas-heel al-Ilmām bi-fiqhil-Ahādeeth min Bulūghil-Marām and is printed in seven volumes.