Reference: Fataawa Mu’aasirah – Page 344
Question: If a caller [to Islaam] invites [someone] to [do] something which he is unable to do himself – even after having tried – but finds the one he is inviting will be able to do it, should he [still] invite him to do it?
Response: If this caller [to Islaam] – who invites [others] to that which is good – is unable to do so himself, then he must [still continue to] invite others to do so. Let us assume [for example], a man invites [others] to [pray] the night prayer, yet he himself is unable to [pray] the night prayer, so you must not say: ‘if you are unable [to pray the night prayer], then don’t invite [others] to [pray] the night prayer’; [similarly], a man invites [others] to [give in] charity while he is unable or does not have anything to give in charity, so we say [to him]: ‘[continue to] invite [others]’. As for something which he invites [others] to [do], and he is [also] able to do himself – but does not do – then no doubt he is mentally foolish and astray in the religion.