Burst of Speed — ruling 1

Burst of Speed affects only creatures you control at the time it resolves. It won’t affect creatures that come under your control later in the turn.

Burst of Speed : règles, fonctionnement et interactions (MTG)

Burst of Speed 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

Creatures you control gain haste until end of turn. (They can attack and even if they just came under your control.)

How it works : Burst of Speed

Original English text — Wizards of the Coast / Scryfall

#1October 1, 2009· Wizards of the Coast
Burst of Speed affects only creatures you control at the time it resolves. It won’t affect creatures that come under your control later in the turn.
No other card is named in this ruling.