Tesla CEO Elon Musk spent more than five hours on the witness stand Monday responding to a volley of questions from an attorney who made it clear he wanted Musk to be more succinct during a Court of Chancery trial, and he’s set to return for more Tuesday.

Musk, who appeared in person at the Leonard L. Williams Justice Center in Wilmington, is the first witness in the trial challenging Tesla’s $2.6 billion 2016 merger with SolarCity, which the plaintiff investors argue was unwarranted and Musk maintains was a strategic move for both companies.