وَاسْتَلَمَهُ وَقَبَّلَهُ إِنِ اسْتَطَاعَ
Translation: He touches and kisses it if he is able.
Istalama and qabbala are past-tense verbs with implicit subjects; -hu is the object pronoun referring to the Stone. In introduces the condition, istaṭāʿa is its verb, and its consequence is understood from the preceding actions.