Firstly, among the etiquettes of supplication is to begin with praise and glorification of Allah, the Beneficent and Responsible, and to seek intercession through the leader of creation (Prophet Muhammad, peace and blessings be upon him) by sending blessings and peace upon him. This is because he is the gateway to acceptance, and sending blessings and peace upon him is a means of acceptance. Allah, the Most High, says: “Those whom they invoke seek means of access to their Lord, [striving as to] which of them would be nearest,” [Al-Isra’, 17:57]. And Allah, the Most High, says: “O you who have believed, fear Allah and seek the means [of nearness] to Him” [Al-Ma’idah, 5:35].
Secondly, the mentioned hadith was narrated by Fadalah bin ‘Ubayd, may Allah be pleased with him, who said: “the Messenger of Allah, peace and blessings be upon him, heard a man who was supplicating in his prayer without praising Allah and without sending blessings upon the Prophet, peace and blessings be upon him. So, he said, ‘Hasten, this one.’ Then he called him and said, ‘When any one of you prays, let him start by praising his Lord and glorifying Him, then let him send blessings upon the Prophet, then let him supplicate as he wishes after that.'” [Reported by Abu Dawood, Ahmad, At-Tirmidhi (who graded it as authentic), Ibn Hibban, and Al-Hakim].
The evident point here is that the key to supplication and the hope for acceptance is left out. This key is the praise, glorification, and sending blessings and peace upon the intercessor (Prophet Muhammad). The hadith does not state that the supplication was not accepted, but rather, it emphasizes the omission of certain etiquettes of supplication that are recommended.
As for the second part of the question concerning supplication during prostration:
So, supplication during prayer does not differ from supplication outside of it in terms of its etiquettes. The variation might only occur in the wording of the request. This is done out of consideration for the differing opinions among scholars regarding what is permissible to use from one’s speech during prayer. Their detailed discussions on this matter are as follows:
Firstly: The jurists unanimously agree on the permissibility of supplicating with the supplications that are mentioned in the Quran and Sunnah, such as: “Our Lord, give us in this world [that which is] good…” [Al-Baqarah, 2:201], “O Allah, I seek refuge in You from disbelief and poverty and from the punishment of the grave.” This type of supplication is referred to as “Mawthoor” (narrated) supplication.
Likewise, the majority of scholars permit supplicating with supplications that resemble the Mawthoor supplications. This means using words that resemble the phrases found in the Quran and Sunnah, such as: “O Allah, we ask You for the righteousness of our sons and daughters.”
Secondly: The jurists have differed regarding the permissibility of supplicating that does not resemble Mawthoor supplications during prayer. This includes supplications for specific worldly matters, such as a particular marriage proposal, obtaining a specific job, visa, or acceptance into a university:
• The majority of scholars have concluded that all of this is permissible during prayer as well as outside of it. They base their argument on the hadith narrated by Ibn Mas’ud, in which it is said, “Then he should choose from the matters what he wishes.” [Reported by Bukhari and Muslim]. This narration is general in its scope, applying to both the Mawthoor supplications and other supplications.
• The Hanbali school of law holds the opinion that supplicating with non-Mawthoor supplications during prayer is not valid because it involves using human speech. The hadith explicitly states that no human speech is valid within the prayer.
• The Hanafi school of law, however, delves into the specifics. They say that what is supplicated for can be categorized as follows:
• Matters that can only be sought from Allah, such as guidance, forgiveness, general sustenance, and entry into paradise, are permissible to be supplicated for in any wording.
• Matters that can be sought from created beings, like a specific job, a car, or marriage to a specific individual, the Hanafi scholars prohibit supplicating for them during prayer. Their stance here is similar to that of the Hanbali school of law.
The correct view is that we are allowed to supplicate for whatever we wish. The term “human speech” refers to speech that goes beyond the confines of prayer or is not in the form of remembrance, while supplication is a form of remembrance. This is the opinion of the Maliki and Shafi’i schools of law. The hadith about “human speech” cannot be specifically applied to exclude supplication, as it contradicts the general statement of Allah: “And your Lord says, ‘Call upon Me…'” [Ghafir, 40:60] and the generality of Ibn Mas’ud’s hadith that was mentioned earlier.
Fatwa by Dr. Khālid Naṣr