Sequence of Verses
Emphasis was laid in previous verses over the fulfillment of the covenant with Allah following which stated there was the importance and desirability of acting righteously in one's life. That one neglects to follow these commandments happens because of Shaitanic instigations. Therefore, this verse teaches us to seek protection against Satan, the accursed - something needed in every good deed. But, it will be noticed that it has been mentioned particularly with the recitation of the Qur’ an. One reason for this particularization could also be that the recitation of the Qur'an is an act so unique that the Satan himself runs away from it. As said poetically:
دیوبگر یزدازاں قوم کہ قرآں خوانند
Shaitan bolts from people who recite the Qur’ an!
Then, there are specified Verses and Chapters which have been-tested and they produce the desired result in removing the traces of Shaitanic inputs particularly. That they are effective and beneficial stands proved from definite textual authorities (nusus) - Bayan al-Qur'an. Despite this factor, when came the command to seek protection from the Satan in conjunction with the recitation of the Qur’ an, it becomes all the more necessary with other deeds.
In addition to that, there is always the danger of Shaitanic instigations intruding into the recitation of the Qur’ an itself. For instance, one may-fall short in observing the etiquette due during the recitation or that it remains devoid of the essential spirit of deliberation, thinking, submission and humbleness. So, for this too, it was deemed necessary that protection from Shaitanic instigations should be sought (Ibn Kathir, Mazhari and others).
Commentary
In the preface of his Tafsir, Ibn Kathir has said: Human beings have two kinds of enemies. The first ones come from their own kind, like the general run of disbelievers. The other kind is that of the Jinn who are diabolic and disobedient. Islam commands defence against the first kind of enemy through Jihad involving fighting and killing. But, for the other kind, the command is limited to the seeking of protection from Allah only. The reason is that the first kind of enemy happens to be homogenous. Its attack comes openly, visibly. Therefore, fighting and killing in Jihad against such an enemy was made obligatory. As for the , enemy of the Satanic kind, it is not visible. Its attack on humankind does not take place frontally. Therefore, as a measure of defence against such an enemy, the seeking of the protection of such a Being has been made obligatory that no one is able to see, neither the humankind, nor the Satan. Then, there is that subtle expediency in entrusting the defence against Satan with Allah. Is it not that one who stands subdued by the Satan is actually rejected and deserving of punishment in the sight of Allah? Quite contrary to this is the case of the humanoid enemy of human beings, that is, the disbelievers. If someone is subdued or killed while con-fronting them, he becomes a martyr (shahid), and deserving of reward from Allah (thawab) ! Therefore, when one confronts an enemy of human beings with all his strength, it turns out to be nothing but beneficial, no matter what the circumstances - either he would prevail over the enemy and put an end to his power, or would himself embrace shahadah (martyrdom in the way of Allah) and deserve the best of returns with Him.
Related Rulings (masa'il)
1\. The reciting of: اعوذ باللہ من الشیطان الرجیم (a udhu bil-lahi minash-shaitanir-rajim: I seek protection with Allah from Shaitan, the accursed) before initiating the recitation of the Qur'an stands proved from the Holy Prophet ﷺ in order that the command given in this verse is carried out.
But, not doing it occasionally also stands proved from authentic (sahih) ahadith. Therefore, the majority of Muslim scholars have not classed this injunction as obligatory (wajib). Instead, they have declared it to be Sunnah, a position on which Ibn Jarir al-Tabari has reported a consensus (ijma`) of the scholars of the Muslim community. As for Hadith narratives carrying the word and deed of the Holy Prophet ﷺ ، whether those of reciting: اعوذ باللہ (a’ udhu bil-lah) under most conditions or those of not reciting under some, all these have been mentioned exhaustively by Ibn Kathir at the beginning of his Tafsir.
2\. Should ta'awwudh (تَعَوُّذ) that is, اعوذ باللہ 'a۔ udhu bil-lah', be recited only at the beginning of the first raka'ah while in Salah, or should it be done at the beginning of every raka'ah? Views of leading Muslim jurists differ in this matter. According to the great Imam Abu Hanifah JI it should be recited only in the first raka'ah while Imam Shafi` i (رح) declares its recitation at the beginning of every raka'ah as commendable (mustahabb). Arguments given by both have been presented in Tafsir Mazhari with full elaboration. (p. 49, v. 5)
3\. While reciting the Qur'an - whether in Salah or out of it - the saying of اعوذ باللہ 'a`-udhu bil-lah' is a Sunnah. The rule applies to both situations equally. But, after it has been said once, one may go on reciting as much as one wishes to, for the same single ta'awwudh (said at the beginning) is sufficient. Yes, if one abandons the recitation in the middle, gets busy with some mundane chore and then resumes it all over again, one should reinitiate the recitation by saying 'a’ udhu bil-lah' and 'bismillah' once again at that time.
4\. Saying 'a’ udhu bil-lah' before reading any word or book other than the Qur'an is not a Sunnah. There, one should recite only bismillah. (Al-Durr al-Mukhtar, Shami)
However, the Hadith teaches the saying of ta'awwudh during other things done and situations faced. For example, when someone gets very angry - so says the Hadith - the heat of the anger goes away by saying: اعوذ باللہ من الشیطان الرجیم (a`-udhu bil-lahi minash-shaitanir rajim: I seek protection with Allah from Shaitan, the accursed). (Ibn Kathir)
It also appears in Hadith that, before going to the toilet, saying:
للھُمَّ اَعُوذُ باللہ مِن الخبُثِ وَ الخّبّایٔث
(Allahumma adhu bika minal-khubuthi wal-khabaith) 0 Allah, I seek protection with you from the foul and the impure is commendable (mustahabb). (Shami)