Is the command in the hadith "Change the white hair" for obligation?

Question:
for obligation?

Answer:
The default ruling for commands is obligation, as the Prophet (peace and blessings be upon him) said in the story of al-Ṣiddīq: . However, it appears from the actions of the Prophet (peace and blessings be upon him) and some of the Companions that it is not obligatory, but rather a confirmed recommended practice (sunnah muakkadah) to change it. This is because there are reports indicating that white hairs could be seen in his beard that he had not changed. Similarly, regarding the Companions (may Allah be pleased with them) , there are reports indicating that they would leave their hair white for days and nights and then change it. Therefore, the most likely view—may Allah know best—is that it is a confirmed recommended practice.
Q: Is the hadith authentic?
The Shaykh: There is nothing wrong with it; its chain of narration is good, there is nothing wrong with it.
Q: Is anyone excepted from this, such as those who say that those fighting in the path of Allah are excepted from this?
The Shaykh: I do not know of any exception in this.