As for bearing witness for a person that he himself is a person of the people of The Fire or of Paradise; then that is not for anyone to do so except with an authentic text which necessitates that. Such as the case of the ten for whom glad tidings of Paradise were given by the truthful one (Sallalaahu ‘alaihi wa sallam). There are those that make it permissible for the one for whom the praises of the Ummah have become widespread – such as ‘Umar bin ‘Abdil-Azeez (radhiyallaahu ‘anhu) and his like.
Indeed some of the Salaf used to prohibit bearing witness of Paradise for other than the Messenger (Sallalaahu ‘alaihi wa sallam) – such that ‘Alee bin Al-Madeenee had a debate with Ahmad (bin Hanbal) concerning this issue saying:
‘I say: that they are in Paradise; however I do not bear witness for specific individuals’.
So Ahmad replied:
‘When you say they are in Paradise you have bore witness that they are in Paradise’.
As for the people withholding in totally bearing witness to a persons being in Paradise; then it is due to a fear of how his end (demise) will be. But despite this we have hope for the doer of good and fear for the doer of bad.
Anyone from whom the actions that Allaah and His Messenger love become apparent; then it is obligatory to make conduct with him from that which is necessary through alliance and love and kindness. Likewise anyone from whom that which is contrary to this becomes apparent; then conduct with him is to be in accordance to its consequences.