Sphinx's Disciple — ruling 1

Inspired abilities trigger no matter how the creature becomes untapped: by the turn-based action at the beginning of the untap step or by a spell or ability.

Sphinx's Disciple — ruling 2

If an inspired ability triggers during your untap step, the ability will be put on the stack at the beginning of your upkeep. If the ability creates one or more token creatures, those creatures won’t be able to attack that turn (unless they gain haste).

Sphinx's Disciple — ruling 3

Inspired abilities don’t trigger when the creature enters the battlefield.

Sphinx's Disciple — ruling 4

If the inspired ability includes an optional cost, you decide whether to pay that cost as the ability resolves. You can do this even if the creature leaves the battlefield in response to the ability.

Sphinx's Disciple : règles, fonctionnement et interactions (MTG)

Sphinx's Disciple is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

Flying Inspired — Whenever this creature becomes untapped, draw a card.

How it works : Sphinx's Disciple

Original English text — Wizards of the Coast / Scryfall

#1February 1, 2014· Wizards of the Coast
Inspired abilities trigger no matter how the creature becomes untapped: by the turn-based action at the beginning of the untap step or by a spell or ability.
No other card is named in this ruling.
#2February 1, 2014· Wizards of the Coast
If an inspired ability triggers during your untap step, the ability will be put on the stack at the beginning of your upkeep. If the ability creates one or more token creatures, those creatures won’t be able to attack that turn (unless they gain haste).
No other card is named in this ruling.
#3February 1, 2014· Wizards of the Coast
Inspired abilities don’t trigger when the creature enters the battlefield.
No other card is named in this ruling.
#4February 1, 2014· Wizards of the Coast
If the inspired ability includes an optional cost, you decide whether to pay that cost as the ability resolves. You can do this even if the creature leaves the battlefield in response to the ability.
No other card is named in this ruling.