Click on the link in this paragraph. It is a summary of Floyd Mayweather's fighting career. The 3rd paragraph in the welterweight section spells it out in black and white my friend. http://en.wikipedia.org/wiki/Floyd_Mayweather_Jr.

You know what, I'll even copy and paste that paragraph into this blog:

Mayweather rejected an offer of US$8 million to fight Antonio Margarito and split with promoter Bob Arum for the possibility of a superfight with Oscar de la Hoya.[22] de la Hoya, however, postponed his decision until 2007, leaving Mayweather in the awkward position of choosing his next opponent, while deflecting accusations that he had ducked Margarito.[23] Mayweather considered moving up in weight again to fight junior middleweight champion Cory Spinks, but because of negative publicity and Spinks' impending mandatory defense of his title, he finally decided to face WBC and The Ring welterweight champion Carlos Baldomir on November 4, 2006 in Las Vegas.[24]