The best policy to adhere to regarding this issue is that imams who are physically challenged and therefore unable to pray standing should delegate the responsibility of leading the Prayer to someone who is qualified to lead, especially when there is no dearth of people who can lead Prayers.
Sheikh Ahmad Kutty, a senior lecturer and Islamic scholar at the Islamic Institute of Toronto, Ontario,
Canada, states: It is best for the imam who is suffering from some physical challenges and is therefore unable to lead the Prayer standing to delegate the responsibility to someone who is qualified to lead. In this way, one can avoid the confusion surrounding the issues of praying behind someone who is sitting because of illness. This is the best policy to adhere to in regards to issues of `ibadat (acts of worship), especially when there is a divergence of opinions on the issue, some scholars permitting it, while others prohibiting.
For while the majority of scholars are of the opinion that if the imam is leading the Prayer sitting, those who follow him must be standing if they are able to stand, others, however, have ruled that the followers must also be sitting while the imam is sitting. The latter group have inferred this from the words of a hadith in which the Prophet (peace and blessings be upon him) reportedly stated, “Imam has been appointed to follow: so if he makes takbir follow him in takbir, if he performs bows, follow him; if he prostrates, prostrate after him; likewise, if he prays sitting, you also pray sitting.”
The above statement, however, is apparently in direct contradiction with another authentic hadith from `A’ishah, the beloved wife of the Prophet (peace and blessings be upon him). According to her, during his final illness, the Prophet (peace and blessings be upon him) led the Prayer while he was sitting, and Abu Bakr as well as other Companions prayed behind him while standing. The first group therefore considers this Prophetic precedent as abrogating his previous order.
In conclusion, the safest way to come out of the controversy is that imams who are physically challenged and therefore unable to pray standing should delegate the responsibility of leading the Prayer to someone else, especially when there is no dearth of people who can lead Prayers. If, however, it is a question of leading Jumu`ah Prayer where there are not many people who are qualified to deliver khutbahs, then a solution can be found if the imam after having delivered the khutbah asks someone else to lead the Prayer.