As we all know, there are certain situations that the Shariah legislated or recommends that we perform GHUSL: The Ghusl of Jumu'ah, Ghusl after observing the menstrual circle, Ghusl after sexual intercourse, among others.
[The proof is what] Aa’ishah (may Allah be pleased with her) said:
The Prophet (sallallaahu alayhi wasallam) did not use to perform ablution after ghusl.”
[Recorded by at-Tirmidhee (107) and an- Nasaa’ee (1/137)].
“He (sallallaahu alayhi wasallam) performed ghusl and offered two rak’ahs of prayer. I do not think he performed ablution afresh after the ghusl.”[Saheeh lighairihi: recorded by Aboo Daawood (250) and Ahmad (6/119)].
Know that this ruling is restricted to ghusl for sexual intercourse (janaabah).
Source: Tamaamul-Minnah fee Fiqh al-Kitaab wa Saheeh as-Sunnah, vol. 1, p. 118, by Abu Abdir-Rahmaan ‘Aadil bin Yoosuf al-Azzaazee.