Praise be to Allah, and peace and blessings be upon the Messenger of Allah.
Belief in the Scale of Deeds on the Day of Judgment is established by the Qur’an and the Sunnah. The texts indicate that it is a real scale with two pans, in which deeds will be weighed. Whoever’s scales are heavy will succeed, and whoever’s scales are light will lose.
The Hadith of the Card mentions that the card will be placed on one pan and the records on the other pan, which proves that the scale has two pans.
As for the claim that the scale has a tongue, this was mentioned by some scholars, and a report to this effect has been attributed to Ibn Abbas, may Allah be pleased with him, and to al-Hasan al-Basri. However, no authentic marfu‘ hadith from the Prophet ﷺ has been established regarding this.
Some scholars have stated that affirming the tongue is based on what people conceive of the physical form of a scale, but there is no clear evidence requiring certainty about this matter.
Therefore, what is prescribed is to believe in the existence of the Scale and its two pans, as indicated by the texts. As for affirming that it has a tongue, it is not correct to assert this with certainty because there is no authentic, marfu‘ evidence establishing it.
And Allah knows best.