[Konstantinos]

Doing the same thing. Getting the name from the player the playerid typed and check it with strcmp (Remember, if it returns 0 - both strings (names) are same).

pawn Код:

CMD:sethealth( playerid, params[ ] )
{
    new
        id,
        Float: health
    ;
    if( sscanf( params, "rf", id, health ) ) return SendClientMessage( playerid, -1, "Usage: /sethealth <ID/Part Of Name> <health>" );
    if( id == INVALID_PLAYER_ID ) return SendClientMessage( playerid, -1, "Offline player" );

    new
        _name[ MAX_PLAYER_NAME ]
    ;
    GetPlayerName( playerid, _name, MAX_PLAYER_NAME );
    if( !strcmp( _name, "Fernado", true ) )
    {
        GetPlayerName( id, _name, MAX_PLAYER_NAME );
        if( !strcmp( _name, "Samuel", true ) ) SetPlayerHealth( id, health );
        else SendClientMessage( playerid, -1, "You can use this command only to Samuel!" );
    }
    else SendClientMessage( playerid, -1, "Only Fernado can use this command!" );
    return 1;
}