Salat-ul-Tahajjud is a voluntary prayer performed after waking up from sleep during the night.

Here’s a brief guide:

1. Timing: Best performed in the last third of the night.
2. Units: Perform 2 or more units (rakats).
3. Intention: Declare your intention to perform Salat-ul-Tahajjud.
4. Recitation: Recite Surah Al-Fatihah and a shorter Surah in each unit.
5. Ruku and Sujud: Perform the usual bowing and prostration.
6. Sitting between Units: Sit briefly after the second unit.
7. Conclusion: End with the final sitting and greeting.

Note: Salat-ul-Tahajjud is optional, and its performance is based on personal devotion and circumstances.