A ft ah , ▁because ▁they ▁un condition ally ▁believed ▁the ▁Im am ate ▁could ▁only ▁be ▁inherited ▁from ▁father ▁to ▁son , ▁rather ▁than ▁from ▁brother ▁to ▁brother . ▁This ▁group ▁also ▁claimed ▁that ▁Muhammad ▁ibn ▁Abd ul lah ▁al - A ft ah ▁was ▁the ▁promised ▁Mah di . ▁ ▁As ▁the ▁family ▁continued ▁to ▁grow , ▁an ▁original ▁family ▁tree ▁of ▁the ▁Pro ph et ▁Muhammad ▁from ▁Im am ▁J af ’ ar ▁as ▁S adi q ▁to ▁his ▁elder ▁son ▁Abd ul lah ▁al ▁A ft ah ▁is ▁given ▁ ▁below . ▁This ▁extensive ▁family ▁tree ▁now ▁extend ▁to ▁the ▁ 3 1 st ▁generation , ▁and ▁more ▁than ▁ 1 0 0 ▁surv iving ▁families ▁throughout ▁most ▁contin ents . ▁ ▁S ā hib ▁al - Ha qq ▁▁ ▁In ▁a ▁letter ▁sent ▁to ▁the ▁Is m ā ʿ ī l ī ▁community ▁in ▁Y emen ▁by ▁Abd ul lah ▁al - M ah di ▁B illa h , ▁which ▁was ▁reprodu ced ▁by ▁Ja ' far ▁bin ▁Mans ū r ▁al - Y emen , ▁ ʿ Ab d ▁All ā h ▁al - A ft ah ▁ibn ▁Ja ʿ far ▁al - S adi q ▁was ▁referred ▁as ▁S ā hib ▁al - Ha qq ▁or ▁the ▁legit imate ▁successor ▁of ▁Im ā m ▁Ja ʿ far ▁al - S adi q ▁by ▁Abd All ā h ▁in ▁an ▁attempt ▁to ▁explain ▁the ▁gene al ogy ▁of ▁his ▁ancest ors . ▁Instead ▁of ▁trac ing ▁his