Writing the ninety-nine names of Allah for the purpose of memorizing them

Question:
Honorable Shaykh, may Allah grant you success, is it prescribed to write these ninety-nine names on a piece of paper and attempt to memorize them?

Answer:
How do you know the ninety-nine? The Messenger (peace and blessings be upon him) did not mention them, but they are derived from the Book of Allah and the Sunnah of the Messenger of Allah (peace and blessings be upon him) through tracing. Al-Hafiz al-Tirmidhi mentioned them at the end of the hadith; he mentioned them at the end of this hadith because this hadith is from al-Tirmidhi’s narration, and he listed them at the end as his own ijtihad (independent legal reasoning). This is not a text from the Messenger (peace and blessings be upon him). They call this an insertion; it is an insertion from al-Tirmidhi’s words, not from the words of the Messenger (peace and blessings be upon him).