Abu Dawud said: The hadith of Muslim is more complete.

1389 – Sulayman ibn Harb narrated to us, Hammad narrated to us, from ‘Ata’ ibn al-Sa’ib, from his father, from ‘Abdullah ibn ‘Amr, who said: The Messenger of Allah, peace and blessings be upon him, said to me: "Fast three days of every month, and recite the Qur’an in a month." Then he reduced it and I reduced it, until he said:—

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It was also recorded by al-Bukhari (5054) and Muslim (1159) via the chain of Muhammad ibn ‘Abd al-Rahman, the freed slave of Banu Zuhrah, from Abu Salamah, with this chain of transmission.

It was also recorded by Muslim (1159) via the chain of Yahya ibn Abi Kathir, from Abu Salamah, with it.

It was also recorded by Ibn Majah (1346) via the chain of Yahya ibn Hakim, al-Tirmidhi (3175) via the chain of Abu Burdah, and al-Nasa’i in al-Kubra (2721) via the chain of Abu al-‘Abbas al-Sa’ib ibn Farrukh — all three of them from ‘Abdullah ibn ‘Amr, with it. However, in the two narrations of Abu Burdah and Abu al-‘Abbas, he permitted him to complete the Qur’an in five days. And permission to recite it in three will come in the following hadith.

It is also in Musnad Ahmad (6876) and Sahih Ibn Hibban (756).

And look at what will follow under numbers (1389), (1390), (1391), (1394), and (1395).

His statement, "And do not exceed that," means: do not change the mentioned state to another state. Thus "increase" was used loosely, while the intended meaning is decrease. The increase here is by way of concession, i.e., he should not recite it in less than seven.

Al-Hafiz said in al-Fath 9/97: It seems that the prohibition against increase is not one of prohibition (of unlawfulness), just as the command in all of that is not one of obligation. This is known from the contextual indications to which the narrative points — namely, consideration of his inability to do more than that, either in the present or in the future. Some of the Zahiris made a strange statement, saying: It is forbidden to recite the Qur’an in less than three. Al-Nawawi said: The majority of scholars hold that there is no fixed limit in this matter; rather, it depends on one’s energy and strength. On this basis, it varies according to circumstances and individuals. See also, necessarily, the treatise "Iqamat al-Hujjah ‘ala anna al-Ikthar fi al-Ta’abbud laysa bi-Bid’ah" by Imam al-Laknawi, edited by the scholarly professor ‘Abd al-Fattah Abu Ghuddah.