One of the last pre-Elon Musk Twitter executives to leave the company said he and the billionaire exchanged ideas at 3 a.m.

• A former Twitter exec said he and Elon Musk used to swap ideas for the site until the early morning.
• Behnam Rezaei, Twitter's head of product and engineering, said he left Twitter this week.

One of the last remaining executives from Twitter 1.0 said Wednesday he and Elon Musk, the company's new owner, used to exchange ideas for the site into the wee hours of the morning.

Behnam Rezaei, Twitter's head of product and engineering, said he left Twitter the previous day. In a thread on the platform, he described his 5 ½ years working at the social-media giant.

As well as discussing his role and praising his former colleagues, Rezaei posted about what it was like to work alongside Musk.

Rezaei said he had worked with Musk "to transform the company towards his vision" and they had exchanged 3 a.m. texts about "product ideas or bugs."

Musk, who is known for his headstrong approach to work, has said he's slept at Twitter's offices since taking over, and other staffers have appeared to sleep there, too. The tech mogul has previously said he sleeps about six hours a night on average, and he often tweets well into the night.

"I also learned from up close Elon Musk's framework to scale the efficiency of a startup to a midsize company to achieve the unachievable," Rezaei tweeted. "Thank you Elon."

While he used the blue-heart emoji and the hashtag #lovewhereyouworked, which have become symbolic among former Twitter staff, Rezaei's tweets are in stark contrast to those of many other Twitter employees who left the company.

Former staffers appear to have largely avoided mentioning Musk in their farewell posts on Twitter and LinkedIn, instead choosing to talk about how they "had it good at Twitter 1.0," a phrase used to refer to the company pre-Musk. Some have tweeted thinly veiled criticisms of the company's new owner.

Rezaei's posts suggests an amicable parting, in contrast to the thousands of Twitter staff who were abruptly laid off the week Musk took charge of the company.

The Platformer journalist Zoë Schiffer said Rezaei had been one of the last remaining leaders at the site from pre-Musk Twitter. Schiffer said Rezaei resigned from the company, though in his tweets, he did not specify whether he quit or was laid off.