Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
Qurʾān Bukhārī Muslim Nasāʾī Abū Dāwūd Tirmidhī Ibn Mājah Mālik Aḥmad Dārimī Ḥākim Ibn Ḥibbān Ṭabarānī Nasāʾī's Kubrá Bayhaqī al-Luʾluʾ wa-al-Marjān Ibn Rajab's Fifty Riyāḍ al-Ṣāliḥīn Aḥmad's Zuhd Suyūṭī
quran:51:23 –

Then by the Lord of the heaven and earth, indeed, it is truth - just as ˹sure as˺ it is that you are speaking.  

So by the Lord of the heaven and the earth, it, that which you are promised, is as assuredly true as ˹the fact˺ that you have ˹power of˺ speech (read mithlu, in the nominative, as an adjective, with the mā being extra; or read mithla, in the accusative, as being a compound with mā), that is to say: ˹it is as true˺ as your speech is in reality, that is, in your knowing it to be ˹true˺ necessarily by its issuing from you.
القرآن:٥١:٢٣ –

فَوَرَبِّ السَّمَاءِ وَالْأَرْضِ إِنَّهُ لَحَقٌّ مِثْلَ مَا أَنَّكُمْ تَنْطِقُونَ  

{فورب السماء والأرض إنه} أي ما توعدون {لحق مثلُ ما أنكم تنطقون} برفع مثل صفة، وما مزيدة وبفتح اللام مركبة مع ما، المعنى: مثل نطقكم في حقيقته أي معلوميته عندكم ضرورة صدوره عنكم.