This is certainly ˹mentioned˺ in the earlier Scriptures— the Scriptures of Abraham and Moses.
I suppose scripture of Moses refers to the Torah, which can be found in the Old Testament. However, what's the scripture of Abraham?
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It is revelation that was sent to him. Its contents include what is mentioned in the Quran:
In Surah Al-A'la, which at least includes the preceding sentence, and could mean the entire surah:
He has certainly succeeded who purifies himself. And mentions the name of his Lord and prays. But you prefer the worldly life, While the Hereafter is better and more enduring. Indeed, this is in the former scriptures, The scriptures of Abraham and Moses.
In Surah An-Najm, which includes at least the ensuing sentence, and could mean the remainder of the surah till the end:
Or has he not been informed of what was in the scriptures of Moses And [of] Abraham, who fulfilled [his obligations] - That no bearer of burdens will bear the burden of another
Apart from that there is a weak hadith which includes some other content:
وأنزل على إبراهيم عشر صحائف، وأنزل على موسى قبل التوراة عشر صحائف
... He sent down to Abraham ten scriptures and he sent down to Moses before the Torah ten scriptures ...
يا رسول الله، ما كانت صحيفة إبراهيم؟، قال: كانت أمثالا كلها: أيها الملك المسلط المبتلى المغرور، إني لم أبعثك لتجمع الدنيا بعضها على بعض، ولكني بعثتك لترد عني دعوة المظلوم، فإني لا أردها ولو كانت من كافر، وعلى العاقل ما لم يكن مغلوبا على عقله أن تكون له ساعات: ساعة يناجي فيها ربه، وساعة يحاسب فيها نفسه، وساعة يتفكر فيها في صنع الله، وساعة يخلو فيها لحاجته من المطعم والمشرب، وعلى العاقل أن لا يكون ظاعنا إلا لثلاث: تزود لمعاد، أو مرمة لمعاش، أو لذة في غير محرم، وعلى العاقل أن يكون بصيرا بزمانه، مقبلا على شأنه، حافظا للسانه، ومن حسب كلامه من عمله، قل كلامه إلا فيما يعنيه
[Abu Dharr] I said: "O Messenger of Allah, what was the Scripture of Abraham ?"
He said: "It was all proverbs, such as:
O powerful and arrogant king, I did not appoint you to pile up worldly gains one on top of another; rather I appointed you to avert from Me the supplication of the one who has been wronged, for I do not reject it even if it comes from a disbeliever.
Every rational individual, unless he loses his mind, must have certain times: a time in which he converses with his Lord, a time in which he takes stock of himself, a time in which he reflects upon the creation of Allah, and a time in which he focuses on meeting his need for food and drink.
Every rational individual should not focus his mind except on three things: seeking provision for the hereafter [by doing righteous deeds], working to earn a living, and finding pleasure in something that is not prohibited.
The intelligent man should have insight into the era in which he lives, focus on his own affairs and guard his tongue.
Whoever regards his words as being among his deeds will speak little and will only speak about what concerns him."
I asked this question in judaism.SE, and received an answer as can be seen in the link.
To best of my understanding, according to the Jewish tradition, Abraham compiled some books/scriptures during his lifetime. I believe these scriptures could be what the Quran is referring to. However, they are now lost, so we don't know the exact contents of them.