Praise be to Allah.
The command in the Prophet’s words “Iqra’u (read, recite)” refers to reading (or reciting) in general terms, whether that is reading from the Mus-haf or reciting by heart (from memory).
“It will come as an intercessor for its companions” means for those who read it (or recite it).
End quote from at-Tayseer Sharh al-Jaami‘ as-Sagheer by al-Minnaawi (1/193).
What is meant by that is constantly and regularly reading (or reciting). This is indicated by the phrase “for its companions”; the companion is one who constantly stays with you.
It says in Fatawa al-Lajnah ad-Daa’imah – vol. 2 (3/125):
Undoubtedly the one who reads the Quran, acts upon its meanings, puts it into practice and recites it correctly, and constantly recites it, will attain the pleasure of Allah and His Paradise, and he will reach the highest levels of Paradise, with the honourable noble scribes, and it will be an intercessor and advocate for its companions who act in accordance with it, whether they memorized the Quran and learned it by heart, or read it from the Mus-haf without memorizing it. This is indicated by the report narrated by Imam Muslim and Ahmad from Abu Umaamah al-Baahili, who said: I heard the Messenger of Allah (blessings and peace of Allah be upon him) say: “Read (or recite) the Quran, for it will come on the Day of Resurrection as an intercessor for its companions.” End quote.
Merely reading (or reciting) the Quran, on its own, is not sufficient to attain its intercession; rather it is essential, in addition to reading (or reciting) it, to act in accordance with it. This is indicated by what is said in the other hadith which was narrated by Muslim (805), according to which the Prophet (blessings and peace of Allah be upon him) said: “The Quran will be brought on the Day of Resurrection, as will its people who used to act in accordance with it, led by Soorat al-Baqarah and Aal ‘Imraan, as if they are two clouds, or two black canopies, with light between them, or as if they are two flocks of birds in ranks, pleading on behalf of their companions.”
It says in Mirqaat al-Mafaateeh Sharh Mishkaat al-Masaabeeh (4/1461):
“who used to act in accordance with it” indicates that those who read (or recite) it but do not act in accordance with it will not be among the people of the Quran, and it will not be an intercessor for them; rather the Quran will be proof against them. End quote.
Shaykh Ibn Baaz (may Allah have mercy on him) said:
The words of the Prophet (blessings and peace of Allah be upon him), “Read (or recite) the Quran, for it will come on the Day of Resurrection as an intercessor for its companions,” were narrated by Muslim in his Saheeh. Its companions are those who act in accordance with it, as it says in the other hadith, in which the Prophet (blessings and peace of Allah be upon him) said: “The Quran will be brought on the Day of Resurrection, as will its people who used to act in accordance with it …”
End quote from Majmoo‘ Fatawa Ibn Baaz (8/156).
What is mentioned above does not mean that a person should not be keen to memorize the Quran, for the one who memorizes the Quran will undoubtedly have an advantage over others, as is indicated by the religious texts. For more information concerning that, please see the answers to questions no. 14035 and 20803.
And Allah knows best.