Update: While this elevated offer has been available for more than a month, there was previously no way to refer someone to the Marriott Bonvoy Business card. Referrals are now live. If you have any Membership Rewards-earning Amex card, you can refer to the Marriott Bonvoy Business card. Referral bonuses vary by card, so be sure to check all of your Amex cards if you have multiple options.
Marriott Bonvoy Business is offering 150,000 points plus a $125 statement credit after spending $8,000 in the first 6 months. That's up from the standard offer of 3 free night awards after spending $6,000 in 6 months. The annual fee is $125. Offer expires 7/15/26.

Amazon Business Prime
Amex Blue Business Cash
Amex Blue Business Plus
Amex Blue Cash Everyday
Amex Blue Cash Preferred
Amex Business Gold
Amex Business Green
Amex Business Platinum
Amex Gold
Amex Graphite Business Cash Unlimited
Amex Green
Amex Platinum
Delta SkyMiles Blue
Delta SkyMiles Gold
Delta SkyMiles Platinum
Delta SkyMiles Reserve
Hilton Honors
Hilton Honors Aspire
Hilton Honors Business
Hilton Honors Surpass
Marriott Bonvoy Bevy
Marriott Bonvoy Brilliant