Abbas - Tanwîr al-Miqbâs min Tafsîr Ibn ‘Abbâs
(But the messenger) Muhammad (pbuh) (and those who believe) in secret and in the open (with him strive with their wealth and their lives) in the way of Allah. (Such are they for whom are the good things) accepted good deeds in the life of this world; it is also said that the good things means: beautiful maidens in the Hereafter. (Such are they who are the successful) those who escape Allah's wrath and torment.
But the Messenger and those who believe with him strive with their wealth and their lives: for them are the good things, in this life and in the Hereafter; those, they are the successful, the triumphant.
(But the Messenger and those who believed with him strove hard and fought) until the end of these two Ayat 9:88-89. This describes the qualities, as well as, the reward of faithful believers. Allah said,
وَأُوْلَـئِكَ لَهُمُ الْخَيْرَاتُ
(Such are they for whom are the good things), in the Hereafter, in the gardens of Al-Firdaws and the high grades.
Maududi - Sayyid Abul Ala Maududi - Tafhim al-Qur'an
"...they do not understand anything now," for they deliberately and intentionally chose the shameful way of staying at home with women, when they were required to go forth for Jihad, though they were healthy, physically fit and well-to-do, and professed Islam. Therefore, according to the Divine Law of Nature. a seal was set upon their hearts and they were bereft of those noble feelings which make one feel ashamed of adopting such a disgraceful conduct.